The correct answer is A. public and private.
Public access specifiers allow access to the member from anywhere in the program. Private access specifiers allow access to the member only from within 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.
Here is a simple example of how access specifiers are used in C++:
“`c++
class Person {
public:
string name;
int age;
private:
string address;
};
int main() {
Person person;
person.name = “John Doe”;
person.age = 30;
// person.address = “123 Main Street”; // Error: private member address cannot be accessed
return 0;
}
“`
In this example, the name and age members of the Person class are public, so they can be accessed from anywhere in the program. However, the address member is private, so it can only be accessed from within the Person class.