What is the purpose of the interface keyword in a programming language?

A) To define a concrete class.

B) To specify a set of methods that implementing classes must provide.

C) To create an abstract class.

D) To allow for multiple inheritance.

Answer: B) To specify a set of methods that implementing classes must provide.

Explanation: The interface keyword is used to define an interface, which is a contract that specifies a set of methods that implementing classes must provide. It does not contain any implementation details, allowing different classes to provide their own implementations of the methods defined in the interface.