Which of the following can be used to create an abstract class in the C++…

To create an abstract class in C++, a class must contain at least one pure virtual function. A pure virtual function is declared by using the syntax = 0 in the function declaration, for example: virtual void func() = 0;. This makes the class abstract, meaning it cannot be instantiated directly. Any derived class must provide an implementation for all pure virtual functions to be instantiable. Now, let's evaluate the options: Option A: Using a pure virtual function in the class — This is correct because it directly creates an abstract class. Option B: Declaring a virtual function in the base class — This is incorrect because a regular virtual function does not make the class abstract; it only enables runtime polymorphism. Option C: Declaring the virtual keyword after the class declaration — This is incorrect because there is no such syntax in C++ to declare 'virtual' after the class name. Option D: More than one of the above — This is incorrect because only Option A is correct. Option E: None of the above — This is incorrect because Option A is correct. Therefore, the correct answer is Option A.