Question du test C++ - Les bases

Que renvoie le code suivant ?

class A {
public:
    void hello() {cout << "A" << endl;}
};

class B : public A {
public:
    void hello() {cout << "B" << endl;}
};

void meet(A a1, A a2) {
    a1.hello();
    a2.hello();
}

int main() {
    B b; 
    A a;
    meet(a, b);
    return 0;
}