This PCAP practice question tests your understanding of strings. 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.
Given s = 'a1b2c3', which TWO of the following expressions return the string '123'?
s[0:5:2]
Why wrong: Returns 'a','b','2' -> 'ab2'.
s[1::2]
Step 2 from index 1: '1', '2', '3'.
s[1:6:2]
Same as A but with explicit end index.
s[0::2]
Why wrong: Returns 'a','b','c' -> 'abc'.
s[2:5:1]
Why wrong: Returns 'b','2','c' -> 'b2c'.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
s[1::2]
Option B is correct because slicing with `s[1::2]` starts at index 1 (the character '1'), goes to the end of the string, and takes every second character, resulting in '1', '2', '3' concatenated as '123'. Option C is also correct because `s[1:6:2]` starts at index 1, stops before index 6 (the string length is 6, so index 6 is just past the last character), and steps by 2, yielding the same sequence of characters.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
s[0:5:2]
Why it's wrong here
Returns 'a','b','2' -> 'ab2'.
s[1::2]
Why this is correct
Step 2 from index 1: '1', '2', '3'.
Related concept
Read the scenario before looking for a memorised answer.
s[1:6:2]
Why this is correct
Same as A but with explicit end index.
Related concept
Read the scenario before looking for a memorised answer.
s[0::2]
Why it's wrong here
Returns 'a','b','c' -> 'abc'.
s[2:5:1]
Why it's wrong here
Returns 'b','2','c' -> 'b2c'.
Common exam traps
Python Institute often tests the misconception that slicing with a step of 2 always starts from index 0, causing candidates to overlook the correct starting index needed to isolate digits from a mixed string.
Detailed technical explanation
Python string slicing uses the syntax `[start:stop:step]`, where negative indices or omitted values can also be used; here, the step of 2 skips every other character. Under the hood, slicing creates a new string object by iterating over the original string's internal character array, which is efficient for small strings but can be memory-intensive for large slices. In real-world parsing, such as extracting numeric digits from alphanumeric identifiers, understanding step slicing is crucial for concise data extraction.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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FAQ
Strings — This question tests Strings — Read the scenario before looking for a memorised answer..
The correct answer is: s[1::2] — Option B is correct because slicing with `s[1::2]` starts at index 1 (the character '1'), goes to the end of the string, and takes every second character, resulting in '1', '2', '3' concatenated as '123'. Option C is also correct because `s[1:6:2]` starts at index 1, stops before index 6 (the string length is 6, so index 6 is just past the last character), and steps by 2, yielding the same sequence of characters.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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