Quick Answer
The answer is 2. This occurs because when Python looks up an attribute on an object, it first checks the instance namespace before checking the class namespace, so the instance attribute `self.x = 2` shadows the class attribute `x = 1`. This concept of instance attribute shadowing class attributes is a fundamental behavior tested on the Certified Associate Python Programmer PCAP exam, often appearing in questions about attribute resolution order and the difference between class-level and instance-level data. A common trap is assuming the class attribute will always be used, but Python’s lookup order prioritizes instance attributes, making the output 2 rather than 1. Remember the mnemonic: “Instance first, class last” — Python always checks the instance’s own attributes before falling back to the class.
This PCAP practice question tests your understanding of object-oriented programming. 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.
class A:
def __init__(self):
self.x = 1
class B(A):
def __init__(self):
super().__init__()
self.x = 2
b = B()
print(b.x)Refer to the exhibit. What will be the output when the code is executed?
class A:
def __init__(self):
self.x = 1
class B(A):
def __init__(self):
super().__init__()
self.x = 2
b = B()
print(b.x)AttributeError
Why wrong: No error; the attribute x is defined.
None
Why wrong: The print statement outputs the integer 2, not None.
1
Why wrong: This would be the value if the B __init__ did not override x.
2
The instance attribute x is set to 2 after the super call.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
2
The code defines a class `MyClass` with a class attribute `x = 1`. The `__init__` method sets an instance attribute `self.x = 2`. When `obj.x` is accessed, Python first looks for an instance attribute, finding `self.x = 2`, so it prints `2`. Option D is correct because instance attributes shadow class attributes.
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.
AttributeError
Why it's wrong here
No error; the attribute x is defined.
None
Why it's wrong here
The print statement outputs the integer 2, not None.
1
Why it's wrong here
This would be the value if the B __init__ did not override x.
2
Why this is correct
The instance attribute x is set to 2 after the super call.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates often confuse class attributes with instance attributes, assuming `x = 1` is always returned, but Python's attribute lookup prioritizes instance attributes over class attributes when both exist.
Trap categories for this question
Command / output trap
The print statement outputs the integer 2, not None.
Detailed technical explanation
In Python, attribute resolution follows the MRO (Method Resolution Order): instance attributes are checked first, then class attributes, then parent classes. This is implemented via `__getattribute__` and `__getattr__` hooks. In real-world code, this pattern is used to set default values via class attributes while allowing per-instance overrides, such as in Django model fields or configuration classes.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
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FAQ
Object-Oriented Programming — This question tests Object-Oriented Programming — Read the scenario before looking for a memorised answer..
The correct answer is: 2 — The code defines a class `MyClass` with a class attribute `x = 1`. The `__init__` method sets an instance attribute `self.x = 2`. When `obj.x` is accessed, Python first looks for an instance attribute, finding `self.x = 2`, so it prints `2`. Option D is correct because instance attributes shadow class attributes.
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 24, 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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