- A
The 'helpers.py' file was added after the Python interpreter started, and sys.modules caching prevents new imports.
Why wrong: sys.modules only caches previously imported modules; a new file will be found on next import.
- B
There is another 'common' package elsewhere in sys.path that shadows the intended one, and the shadowed package does not have a 'helpers' submodule.
If another directory with a 'common' package appears earlier in sys.path, Python imports that one instead.
- C
The PYTHONPATH environment variable is not set, so the /opt/app/ directory is not searched.
Why wrong: It was stated that sys.path includes /opt/app/, so it is searched.
- D
The 'common' package itself is already imported and cached, so adding a new module does not become visible.
Why wrong: Adding a new module to an already imported package is allowed; the package object updates.
PCAP Modules and Packages Practice Question
This PCAP practice question tests your understanding of modules and packages. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company has a large Python application that uses multiple packages from different directories. The application's main entry point is at /opt/app/main.py. There is a package 'common' located at /opt/app/common/ and another package 'services' at /opt/app/services/. Both packages have __init__.py files. Additionally, there is a third-party package 'utils' installed in the system site-packages. Recently, a developer added a new module 'helpers.py' to the 'common' package. When trying to import 'common.helpers' from a script inside 'services', an ImportError is raised: 'No module named common.helpers'. However, importing 'common' itself works. The sys.path includes /opt/app/ and the site-packages. What is the most likely cause of the import failure?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
There is another 'common' package elsewhere in sys.path that shadows the intended one, and the shadowed package does not have a 'helpers' submodule.
Option B is correct because the most likely cause is that a different 'common' package (without a 'helpers' submodule) appears earlier in sys.path and shadows the intended /opt/app/common/ package. Since sys.path includes /opt/app/ and site-packages, if a 'common' package exists in site-packages or another directory listed before /opt/app/, Python will import that shadowed package instead, and it lacks the newly added 'helpers' module. This explains why importing 'common' succeeds (the shadowed package exists) but 'common.helpers' fails.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The 'helpers.py' file was added after the Python interpreter started, and sys.modules caching prevents new imports.
Why it's wrong here
sys.modules only caches previously imported modules; a new file will be found on next import.
- ✓
There is another 'common' package elsewhere in sys.path that shadows the intended one, and the shadowed package does not have a 'helpers' submodule.
Why this is correct
If another directory with a 'common' package appears earlier in sys.path, Python imports that one instead.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The PYTHONPATH environment variable is not set, so the /opt/app/ directory is not searched.
Why it's wrong here
It was stated that sys.path includes /opt/app/, so it is searched.
- ✗
The 'common' package itself is already imported and cached, so adding a new module does not become visible.
Why it's wrong here
Adding a new module to an already imported package is allowed; the package object updates.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Python Institute often tests the subtlety that a package can be shadowed by another package with the same name earlier in sys.path, leading to successful import of the parent but failure for submodules that exist only in the intended package.
Detailed technical explanation
How to think about this question
When Python imports a submodule like 'common.helpers', it first locates the parent package 'common' by scanning sys.path in order. If a different 'common' package (e.g., in site-packages) is found before /opt/app/common/, that package's __path__ is used to resolve 'helpers', and if it lacks the file, an ImportError is raised. This behavior is governed by the module search algorithm in PEP 302 and the importlib machinery, where the first match in sys.path wins, regardless of intended directory structure.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Questions learners often ask
What does this PCAP question test?
Modules and Packages — This question tests Modules and Packages — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: There is another 'common' package elsewhere in sys.path that shadows the intended one, and the shadowed package does not have a 'helpers' submodule. — Option B is correct because the most likely cause is that a different 'common' package (without a 'helpers' submodule) appears earlier in sys.path and shadows the intended /opt/app/common/ package. Since sys.path includes /opt/app/ and site-packages, if a 'common' package exists in site-packages or another directory listed before /opt/app/, Python will import that shadowed package instead, and it lacks the newly added 'helpers' module. This explains why importing 'common' succeeds (the shadowed package exists) but 'common.helpers' fails.
What should I do if I get this PCAP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This PCAP practice question is part of Courseiva's free Python Institute certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCAP exam.
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