The correct choice is the snippet that imports `ABC` and `abstractmethod` from the `abc` module, then defines `Plugin(ABC)` with `@abstractmethod` above `def execute(self): pass`. This works because `ABC` sets the class’s metaclass to enforce abstraction, while `@abstractmethod` marks the method as a contract that every concrete subclass must override; without `ABC`, the decorator is ignored, and without the decorator, subclasses can inherit a no-op method without error. On the PCAP exam, this pattern tests your understanding of the `abc` module’s role in designing plugin systems or frameworks where subclass behavior must be guaranteed—a common trap is forgetting that `@abstractmethod` alone does nothing unless the class inherits from `ABC`. Remember the mnemonic: “ABC and abstractmethod are a pair—without both, your contract is bare.”
PCAP Object-Oriented Programming Practice Question
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 developer designs a plugin system where each plugin must implement a method 'execute'. Which code snippet correctly enforces that subclasses provide an implementation using the 'abc' module?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
from abc import ABC, abstractmethod
class Plugin(ABC): @abstractmethod
def execute(self): pass
Option C is correct because it uses both `ABC` as the metaclass and `@abstractmethod` decorator to enforce that subclasses must override the `execute` method. Without `ABC`, the `@abstractmethod` decorator has no effect; without `@abstractmethod`, the method is just a regular method that can be inherited without being overridden. This combination ensures that any concrete subclass that does not implement `execute` will raise a `TypeError` at instantiation time.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
from abc import abstractmethod
class Plugin: @abstractmethod
def execute(self): pass
Why it's wrong here
Missing inherit from ABC; @abstractmethod alone doesn't prevent instantiation.
✗
from abc import ABC
class Plugin(ABC): def execute(self): pass
Why it's wrong here
Without @abstractmethod, execute is just a normal method.
✓
from abc import ABC, abstractmethod
class Plugin(ABC): @abstractmethod
def execute(self): pass
Why this is correct
This enforces that subclasses must implement execute to be instantiated.
Related concept
Read the scenario before looking for a memorised answer.
✗
class Plugin: def execute(self): raise NotImplementedError
Why it's wrong here
This does not prevent instantiation; it only raises error at call time.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Python Institute often tests the misconception that importing `abstractmethod` alone is sufficient to enforce abstraction, or that raising `NotImplementedError` in a base method is equivalent to using the `abc` module, when in fact only the combination of `ABC` and `@abstractmethod` provides compile-time-like enforcement at instantiation.
Detailed technical explanation
How to think about this question
Under the hood, `ABC` uses `ABCMeta` as its metaclass, which registers abstract methods via the `__isabstractmethod__` attribute. When `@abstractmethod` is applied, it sets `__isabstractmethod__ = True` on the function; `ABCMeta` then checks this attribute during `__init_subclass__` and `__call__` to prevent instantiation of classes that have not overridden all abstract methods. A subtle behavior is that `@abstractmethod` can be combined with other decorators like `@classmethod` or `@staticmethod`, but the order matters — `@abstractmethod` must be the innermost decorator to work correctly.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Object-Oriented Programming — This question tests Object-Oriented Programming — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: from abc import ABC, abstractmethod
class Plugin(ABC): @abstractmethod
def execute(self): pass — Option C is correct because it uses both `ABC` as the metaclass and `@abstractmethod` decorator to enforce that subclasses must override the `execute` method. Without `ABC`, the `@abstractmethod` decorator has no effect; without `@abstractmethod`, the method is just a regular method that can be inherited without being overridden. This combination ensures that any concrete subclass that does not implement `execute` will raise a `TypeError` at instantiation time.
What should I do if I get this PCAP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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