单选题：下列程序段的输出结果是

下列程序段的输出结果是 @[C](2)
```c++
#include
int main(void)
{
int m, k = 0, s = 0;
for (m = 1; m <= 4; m++) {
switch (m % 4) {
case 0:
case 1: s += m; break;
case 2:
case 3: s -= m; break;
}
k += s;
}
printf("%d\n", k);
return 0;
}
```
A. 10
B. -2
C. -4
D. -12





A.10
B.-2
C.-4
D.-12


答案：C