The correct answer is A. public and private.
Public access specifiers allow access to the member from anywhere in the program. Private access specifiers restrict access to the member from outside the class in which it is declared.
Option B, int and double, are data types. Option C, formal and informal, are not access specifiers. Option D, void and free, are keywords in C++.
Here is a simple example of how public and private access specifiers are used in C++:
“`c++
class Person {
public:
string name;
int age;
private:
string address;
};
int main() {
Person p1;
p1.name = “John Doe”;
p1.age = 30;
// p1.address = “123 Main Street”; // Error: address is private
return 0;
}
“`
In the above example, the name and age of the person are accessible from anywhere in the program, but the address is only accessible from within the Person class.