Question 54 of 498
PCEP Control Flow, Loops, Lists and Logic Practice Question
Given the code: x = [1, 2, 3] y = x y.append(4)
print(x)
What is the output?
⚠ Common exam trap
Python Institute often tests the distinction between variable assignment and object copying, trapping candidates who mistakenly think `y = x` creates a separate copy of the list, leading them to choose option B.
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
✓
[1, 2, 3, 4]
In Python, variables hold references to objects, not the objects themselves. When `y = x` is executed, both `x` and `y` point to the same list object in memory. The `y.append(4)` method modifies that shared list in-place, so the change is reflected when `x` is printed, outputting `[1, 2, 3, 4]`.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Error
Why it's wrong here
No error.
- ✗
[1, 2, 3]
Why it's wrong here
Incorrect because x is modified.
- ✓
[1, 2, 3, 4]
Why this is correct
Correct due to aliasing.
- ✗
[1, 2, 3, 4, 5]
Why it's wrong here
Only one element appended.
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Last reviewed: Jun 30, 2026
This PCEP 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 PCEP exam.
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