有以下程序

#include <stdio.h>

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);

}

程序的运行结果是

A)a=1 , b=0

B)a=2, b=2

C)a=1, b=1

D)a=2, b=1