Which of the following functions can be invoked by an object of class D?

Consider the class inheritance.
```
class B
{
public:
B();
B(int nn);
void f();
void g();
private:
int n;
};
class D: public B
{
public:
D(int nn, float dd);
void h();
private:
double d;
};
```

a) f()
b) g()
c) h()

a) f()
b) g()
c) h()