Quick Answer
The answer is the Method Resolution Order (MRO), which Python uses to determine which parent class method is executed in a multiple inheritance scenario. This is correct because Python applies the C3 linearization algorithm to compute a consistent, left-to-right search order through the inheritance hierarchy; when a method is called on a child instance, Python walks the MRO and executes the first matching implementation it encounters, ensuring predictable behavior even in complex diamond patterns. On the Certified Associate Python Programmer PCAP exam, this concept tests your understanding of how Python resolves method conflicts in multiple inheritance, often appearing in questions where two parent classes define the same method name—a common trap is assuming the child must override the method or that Python uses depth-first search. To remember the rule, think "MRO: leftmost parent wins first, then up the chain," or use the mnemonic "My Rightful Order" to recall that the order is computed, not guessed.
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.
A class inherits from two parent classes that both have a method with the same name. When calling the method on the child, only one parent's version is executed. What Python mechanism determines which one?
Method overloading by signature.
Why wrong: Python does not support method overloading.
Explicit super() call in the child class.
Why wrong: super() is used to call parent methods, but it follows MRO.
Inheritance depth (closest parent wins).
Why wrong: MRO considers multiple factors, not just depth.
Method Resolution Order (MRO).
MRO determines the order of method lookup in multiple inheritance.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Method Resolution Order (MRO).
Python uses the C3 linearization algorithm to compute the Method Resolution Order (MRO) for a class. When a method is called on an instance, Python searches the MRO from left to right and executes the first implementation it finds. This ensures a consistent and predictable order of inheritance, even in diamond or multiple-inheritance scenarios.
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.
Method overloading by signature.
Why it's wrong here
Python does not support method overloading.
Explicit super() call in the child class.
Why it's wrong here
super() is used to call parent methods, but it follows MRO.
Inheritance depth (closest parent wins).
Why it's wrong here
MRO considers multiple factors, not just depth.
Method Resolution Order (MRO).
Why this is correct
MRO determines the order of method lookup in multiple inheritance.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Python Institute often tests the misconception that Python uses 'closest parent wins' or depth-first search, but the actual mechanism is the C3 linearization MRO, which respects base class order and the diamond inheritance pattern.
Detailed technical explanation
The C3 linearization algorithm used by Python's MRO ensures that a class always appears before its parents, and that if multiple parents share a common ancestor, that ancestor appears only once and after all its descendants. This prevents inconsistent ordering and the 'diamond problem' that plagues languages like C++. In practice, you can inspect the MRO of any class using `ClassName.__mro__` or `ClassName.mro()`, which returns a tuple of classes in the exact search order.
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: Method Resolution Order (MRO). — Python uses the C3 linearization algorithm to compute the Method Resolution Order (MRO) for a class. When a method is called on an instance, Python searches the MRO from left to right and executes the first implementation it finds. This ensures a consistent and predictable order of inheritance, even in diamond or multiple-inheritance scenarios.
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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Same concept, more angles
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Variation 1. A developer creates classes `A`, `B(A)`, `C(A)`, and `D(B, C)`. When calling a method from `D` that is defined in `A`, which class's version is used according to Python's MRO?
mediumWhy D: Python's Method Resolution Order (MRO) for class `D(B, C)` follows the C3 linearization algorithm, which ensures a depth-first left-to-right search while preserving monotonicity. For `D(B, C)`, the MRO is `D -> B -> C -> A`, so a method defined in `A` that is not overridden in `B` or `C` will be found via `B` first, then `C`, and finally `A`. Option D correctly states that the method from `A` is used, found through `B` then `C`, which matches the actual resolution path.
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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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