单选题：下面程序的运行结果是（）‌#include“stdio.h”‌main()‌{charch[]={“ab”};‌inti，s=;‌for(i=;ch[i]>=’’&&ch[i]<=’′;i+=)‌s=*s+ch[i]‘’;‌printf(“%dn”，s);‌}‌ABCabD