Q: Which of these keywords must be used to inherit a class?  

In Java (and many other object-oriented languages), the extends keyword is used to inherit a class. This keyword allows a subclass to inherit properties and methods from a superclass, promoting code reuse and establishing a relationship between the two classes.

Explanation:

• A) super: This keyword is used to refer to the superclass's methods and constructors, but it does not create inheritance.
• B) this: This keyword is used within a class to refer to the current instance, but it is unrelated to inheritance.
• C) extent: This is not a keyword in Java.
• D) extends: This is the correct answer, as it establishes a parent-child relationship by allowing a subclass to inherit from a superclass.