PCEP Computer Programming and Python Fundamentals Practice Question
Given the code: a = [1, 2, 3]; b = a; b.append(4). What is the value of a?
⚠ Common exam trap
The trap here is that Cisco tests whether candidates understand that assignment with `=` does not create a new copy for mutable objects; many mistakenly think `b = a` creates a separate list, leading them to choose option C.
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 copies. When `b = a` is executed, both `a` and `b` point to the same list object in memory. The `append()` method modifies the list in-place, so the change is visible through both references. Thus, `a` becomes `[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.
- ✓
[1, 2, 3, 4]
Why this is correct
Both a and b refer to the same list.
- ✗
Error
Why it's wrong here
No error.
- ✗
[1, 2, 3]
Why it's wrong here
b is not a copy; it's a reference.
- ✗
[1, 2, 3, [4]]
Why it's wrong here
append adds element, not nested list.
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Written by Johnson Ajibi, MSc IT Security
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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.