单选题 In class MyDERIVED, the number of protected members is ( )class MyBASE {private: int k;public: void set(int n) { k = n; } int get( ) const { return k; }};class MyDERIVED : protected MyBASE {protected: int j;public: void set(int m, int n) { MyBASE::set(m); j = n; } int get( ) const { return MyBASE::get( ) + j; }}