有以下程序：#include ＜iostream＞using namespace std;class sampleprivate: int x; static int y;public: sample(int a); static void print(sample s);;sample:: sample(int a) x=a; y+=x;void sample:: print(sample s) cout＜＜ x= ＜＜s. x＜＜ ,y= ＜＜y＜＜end1;int sample:: y=0;int main() sample s1(10); sample s2(20); sample:: print(s2); return 0;程序运行后的输出结果是( )。
A．x=10,y=20
B．x=20,y=30
C．x=30,y=20
D．x=30,y=30