The correct choice is a relative import, specifically from .sub2 import helper, because when a sibling package uses a bare name like from sub2 import helper, Python searches the top-level module namespace rather than the parent package’s subpackages. Since sub2 is not installed as an independent top-level module, the import fails with an ImportError. This concept tests your understanding of Python’s module resolution order and the importance of explicit relative imports within packages, a common trap on the Certified Associate Python Programmer PCAP exam. The exam often presents a scenario where a subpackage tries to import from a sibling, and the trick is remembering that without a dot prefix, Python assumes an absolute import. A helpful memory tip: think of the dot as saying “look next to me in the same folder,” so from .sibling import module always resolves within the parent package.
PCAP Modules and Packages Practice Question
This PCAP practice question tests your understanding of modules and packages. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 package 'mypackage' has subpackages 'sub1' and 'sub2'. In sub1/__init__.py, there is: from sub2 import helper. When importing mypackage, an ImportError occurs: No module named 'sub2'. What is the most likely cause?
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 the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The import should be from .sub2 import helper (relative import).
Option D is correct because when a subpackage (sub1) tries to import from a sibling subpackage (sub2) using a bare name (from sub2 import helper), Python looks for 'sub2' as a top-level module, not as a sibling within the same parent package. Since 'sub2' is not installed as a top-level module, an ImportError occurs. Using a relative import (from .sub2 import helper) explicitly tells Python to look for sub2 as a sibling package under the same parent, resolving the import correctly.
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.
✗
Sub2 is not installed in the Python environment.
Why it's wrong here
sub2 is part of the package, not an external module.
✗
Sub2 must be imported before sub1 in the package's __init__.py.
Why it's wrong here
Import order does not affect module resolution.
✗
Sub1 should not have an __init__.py file.
Why it's wrong here
Subpackages require __init__.py.
✓
The import should be from .sub2 import helper (relative import).
Why this is correct
Relative imports are required to locate sibling packages within a package.
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.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Python Institute often tests the distinction between absolute and relative imports in packages, trapping candidates who assume that sibling subpackages are automatically visible to each other without using dot-based relative imports.
Detailed technical explanation
How to think about this question
In Python's import system, when a package is loaded, its __init__.py is executed, and any bare import (e.g., 'from sub2 import helper') triggers a search in sys.path, which includes the current working directory and site-packages, but not the parent package's namespace. Relative imports (using dots) leverage the __package__ attribute to resolve siblings within the same parent, which is essential for intra-package references. This behavior is defined in PEP 328 and is critical for structuring large projects with multiple subpackages.
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.
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: The import should be from .sub2 import helper (relative import). — Option D is correct because when a subpackage (sub1) tries to import from a sibling subpackage (sub2) using a bare name (from sub2 import helper), Python looks for 'sub2' as a top-level module, not as a sibling within the same parent package. Since 'sub2' is not installed as a top-level module, an ImportError occurs. Using a relative import (from .sub2 import helper) explicitly tells Python to look for sub2 as a sibling package under the same parent, resolving the import correctly.
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.
About these practice questions
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Given package structure: pack/__init__.py, pack/subpack/__init__.py, pack/subpack/mod.py. Inside pack/__init__.py, which import statement correctly imports mod.py using a relative import?
hard
A.from . import subpack.mod
B.from subpack import mod
C.from ..subpack import mod
✓ D.from .subpack import mod
Why D: Option D is correct because `from .subpack import mod` uses a leading dot to indicate a relative import from the current package (`pack`), then navigates into `subpack` and imports `mod`. This is the proper syntax for importing a module from a subpackage within the same parent package.
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Question Discussion
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