要求函数的功能是交换x和y中的值,且通过正确调用实现x和y的交换。能正确实现此功能的函数是 A. void funa(int *x , int *y) { int t=*y; *y = *x; *x = t; } B. void funa(int *x , int *y) { int t = *x; *x = *y; *y = t; } C. void funa(int x , int y) { int t; t=x;x=y;y=t; } D. int funa(int *x , int *y) { *x=*y;*y=*x; } E. int funa(int *x , int *y) { x = y; y = x; } F. int funa(int x , int y) { x = y; y = x; }