单项选择题

有以下程序: #include <iostream> using namespace std; class BASE { private: char c; public: BASE(char n):c(n);{} virtual~BASE() { cout<<c; } }; class DERIVED:public BASE { char c; public: DERIVED(char n):BASE(n+1),c(n){} ~DERIVED(){cout<<c; } }; int main() { DERIVED obj(’X’); return 0; } 执行上面的程序将输出( )。

A.XY
B.YX
C.X
D.Y