18.
(4分)以下程序的运行结果是( )void sub (int x,int y,int *z){*z=y-x;}main(){int a,b,c;sub(10,5,&a);sub(7,a,&b);sub(a,b,&c);printf(.%4d,%4d,%4d.,a,b,c);}

A. 5, 2, 3
B. -5, -12, -7
C. -5, -12, -17
D. 5, -2, -7