十进制数215用二进制数表示是

A．1100001

B．11011101

C．0011001

D．11010111

有如下程序：
#include ＜iostream＞
using namespace std;
class Baseprivate:
char c;
public:
Base(char n) :c(n)
～Base()

cout＜＜c;
;
class Derived: public Baseprivate:
char c; public:
Derived(char n):Base(n+1),c(n)
～Derived()

cout＜＜c;

;
int main () Derived obj (’x’);
return 0;执行上面的程序净输出

A．xy

B．yx

C．x

D．y