In the context of OOP, what is the "Liskov Substitution Principle"?

A) A subclass must be able to substitute its parent class without affecting the program's functionality.

B) A subclass can have additional properties not present in its parent class.

C) A method can have different implementations in different classes.

D) Classes should not depend on abstract classes.

Answer: A) A subclass must be able to substitute its parent class without affecting the program's functionality.

Explanation: The Liskov Substitution Principle (LSP) is one of the SOLID principles of object-oriented design. It states that objects of a superclass should be replaceable with objects of a subclass without affecting the correctness of the program. This principle ensures that a subclass extends the behavior of the parent class without altering the desirable properties of the program.