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    Question

    Which type of relationship between classes in OOP is

    best represented when one class is a part of another class but can exist independently?
    A Aggregation Correct Answer Incorrect Answer
    B Inheritance Correct Answer Incorrect Answer
    C Composition Correct Answer Incorrect Answer
    D Association Correct Answer Incorrect Answer
    E Polymorphism Correct Answer Incorrect Answer

    Solution

    Aggregation is a type of association that represents a "whole-part" relationship between two classes. The key characteristic is that the part (child object) can exist independently of the whole (parent object). For instance, in a Team class and Player class, a Player can exist without being associated with a Team . Aggregation is implemented by using references, where one class has an attribute referencing another class. This design principle promotes flexibility and modularity. Aggregation is often represented with a hollow diamond in UML diagrams. Why Other Options Are Wrong Option B : "Inheritance" Inheritance represents an "is-a" relationship, not a "whole-part" relationship. It is used to share functionality between classes, not to model part-whole dependencies. Option C : "Composition" Composition is similar to aggregation but with a crucial difference: the part cannot exist independently of the whole. For example, a Car and its Engine share a composition relationship because an engine has no meaning outside the car. Option D : "Association" Association is a broader concept that describes any relationship between classes. Aggregation is a specific type of association. Option E : "Polymorphism" Polymorphism is unrelated to class relationships and focuses on method behavior.

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