Final answer:
In OOP, IS-A association is implemented by inheritance, where one class acquires properties and behaviors of another to form a hierarchical relationship.
Step-by-step explanation:
In Object-Oriented Programming (OOP), an IS-A association is implemented by inheritance. Inheritance allows one class to acquire the properties and behaviors of another class, establishing a hierarchy between classes. The concept of 'IS-A' is fundamental in forming relationships where one class is a subtype of another, suggesting that the derived class 'is a' type of the base class.
For example, if 'Dog' is a class derived from a base class 'Animal', the relationship can be understood as 'Dog IS-A Animal'. This relationship is implemented in code using inheritance, where 'Dog' would inherit attributes and methods from 'Animal'.