The correct answer is: A. always
A constructor is a special type of method that is used to initialize an object of a class. It is called when an object is created. The constructor for a derived class must always be provided, even if the base class constructor does not require arguments. This is because the derived class constructor must call the base class constructor in order to initialize the base class members.
If the base class constructor does not require arguments, then the derived class constructor can simply call the base class constructor without any arguments. However, if the base class constructor requires arguments, then the derived class constructor must provide arguments that match the arguments of the base class constructor.
For example, consider the following code:
“`class Base {
public:
Base() {
cout << “Base constructor called” << endl;
}
};
class Derived : public Base {
public:
Derived(int x) {
Base::Base();
cout << “Derived constructor called with argument ” << x << endl;
}
};
int main() {
Derived d(10);
return 0;
}
“`
In this code, the Derived constructor calls the Base constructor with the argument 10. This is because the Base constructor requires an argument, and the Derived constructor must provide an argument that matches the argument of the base class constructor.
The output of this code is:
Base constructor called
Derived constructor called with argument 10