Foundation concepts: which statement about objects and classes is correct?
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AAn object is an instance of a class.
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BA class is an instance of an object.
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CAn object includes encapsulates only data.
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DA class includes encapsulates only data.
Answer
Correct Answer: An object is an instance of a class.
Explanation
Introduction / Context:Objects and classes are the bedrock of object-oriented analysis and design. A class defines a type (its structure and behavior), and objects are concrete instances of that type that exist at runtime with specific state.
Given Data / Assumptions:
- Classes define attributes and operations.
- Objects realize those definitions with concrete values and identity.
- Encapsulation applies to both, but neither limits “only data.”
Concept / Approach:Distinguish type vs. instance. The type (class) is a blueprint; the instance (object) is a realized entity in memory or persistence with its own attribute values. Therefore, the precise, universally correct statement is that an object is an instance of a class.
Step-by-Step Solution:
Reject statements reversing the type–instance relationship.Reject statements that claim “only data”; objects and classes include data and behavior.Select the accurate pairing: object → instance of class.Verification / Alternative check:In code, declaring “new Customer()” creates an object (instance) of class Customer; many such objects can exist simultaneously.
Why Other Options Are Wrong:Class is an instance of an object is backwards. Only data ignores methods/behavior, which are intrinsic in OO.
Common Pitfalls:Assuming a class is merely a “record structure”; in OO it encapsulates both data and operations.
Final Answer:An object is an instance of a class.