Question: Which of the following is used to make an abstract class?
[A]. Declaring it abstract using static keyword.
[B]. Declaring it abstract using virtual keyword.[C]. Making at least one member function as virtual function.
[D]. Making at least one member function as pure virtual function.
[B]. Declaring it abstract using virtual keyword.[C]. Making at least one member function as virtual function.
[D]. Making at least one member function as pure virtual function.
Answer: Option D