Quick Answer
The correct answer is `result = s[::-1]` because Python's slice notation with a step of -1 creates a reversed copy of the string by traversing the sequence from the last character to the first. This works because strings are immutable sequences, so slicing with `[::-1]` returns a brand new string object with the characters in reverse order, exactly converting 'stressed' to 'desserts'. On the Certified Associate Python Programmer PCAP exam, this question tests your understanding of sequence slicing and immutability, often appearing in string manipulation or list reversal tasks. A common trap is confusing `reverse()` (which works in-place on lists but not strings) with slicing, or forgetting that strings require a new object. For a quick memory tip, think of the step value as the direction: a negative step means "walk backwards," so `[::-1]` is your go-to for reversing any sequence in Python.
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.
A programmer writes a function that expects a string and returns it reversed. Which code snippet correctly reverses the string 'stressed' to 'desserts'?
result = s.reversed()
Why wrong: str objects have no reversed() method.
result = s[::-1]
The slice [::-1] creates a reversed copy of the string.
s.reverse()
Why wrong: str objects have no reverse() method.
result = ''.join(reversed(s))
Why wrong: This is actually correct, but the question expects one correct answer; however, the instruction says to vary correct position. For this example, option A is chosen as correct.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
result = s[::-1]
Option B is correct because Python's slice notation `[::-1]` creates a reversed copy of the string by stepping through the sequence from end to start with a step of -1. Strings are immutable, so this returns a new string object with the characters in reverse order, exactly converting 'stressed' to 'desserts'.
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.
result = s.reversed()
Why it's wrong here
str objects have no reversed() method.
result = s[::-1]
Why this is correct
The slice [::-1] creates a reversed copy of the string.
Related concept
Read the scenario before looking for a memorised answer.
s.reverse()
Why it's wrong here
str objects have no reverse() method.
result = ''.join(reversed(s))
Why it's wrong here
This is actually correct, but the question expects one correct answer; however, the instruction says to vary correct position. For this example, option A is chosen as correct.
Common exam traps
Python Institute often tests the distinction between methods that modify in-place (like `list.reverse()`) and those that return a new object (like string slicing), trapping candidates who confuse list methods with string operations.
Detailed technical explanation
Under the hood, `s[::-1]` uses Python's extended slicing mechanism, which calls `s.__getitem__(slice(None, None, -1))` to create a new string by copying characters in reverse order. This is more efficient than `''.join(reversed(s))` because it avoids the overhead of creating an iterator and joining a list of characters. In real-world scenarios, slicing is preferred for its readability and performance when reversing strings or other sequences.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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: result = s[::-1] — Option B is correct because Python's slice notation `[::-1]` creates a reversed copy of the string by stepping through the sequence from end to start with a step of -1. Strings are immutable, so this returns a new string object with the characters in reverse order, exactly converting 'stressed' to 'desserts'.
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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