以下正确的函数定义是( )。
A. double fun(int x,int y) {z=x+y;return z;}
B. double fun(int x,y) {int z;return z;}
C. fun(x,y) {int x,y;double z; z=x+y;return z;}
D. double fun(int x,int y) {double z;z=x+y; return z;}
#includeint fun1(int a,int b,int c);int main(){ int a=11,b=21,c=31; fun1(a,b,c); printf("%d %d %d\n",a,b,c); return 0; }int fun1(int a,int b,int c){ a=a+10; b=b+10; c=c+10; return c;}
A. 11 21 31
B. 21 11 31
C. 11 31 21
D. 31 21 11