有以下程序,程序的运行结果是( )int main(){int x=1,y=0,a=0,b=0;switch(x){case 1: switch(y){case 0: a++;break;case 1: b++;break;}case 2: a++;b++;break;case 3: a++;b++;}printf(“a=%d,b=%d\n”,a,b);}

A. a=1,b=0
B. a=2,b=2
C. a=1,b=1
D. a=2,b=1