Which of the following is a correct syntax for defining a class in C++?

Correct option is D

In C++, the correct syntax for defining a class includes the class keyword followed by the class name, curly braces containing class members, and a semicolon at the end. Thus, class A { int x; }; is the correct syntax for defining a class with a member variable x.
Important Key Points:
1. Syntax Structure: In C++, the class keyword is used to define a class, followed by the class name and the body enclosed in {}.
2. Semicolon Requirement: C++ requires a semicolon ; at the end of the class definition.
3. Member Variables: Class members like variables and functions are declared within the class body.
Knowledge Booster:
· class B;: Missing the class body and semicolon at the end; incomplete class definition.
· public class A{}: In C++, public is used as an access specifier within the class, not before the class keyword as in some other languages.
· class B{}; public class A{}: Incorrect because C++ does not use public before the class keyword in the way that languages like Java do.
· ObjectA(int x);: This appears as a constructor declaration, not a class definition.