struct point{int x;int y;};struct rect{struct point ldpoint; //左下角struct point rupoint; //右上角}r1={{1,2},{3,4}}, *pr1=&r1;以下语句使用正确的是_____

A. printf("left down point:%d, %d; right up point:%d, %d\n", r1.ldpoint, r1.rupoint);
B. printf("%d\n", pr1.ldpoint.x);
C. printf("%d\n", pr1->rupoint->x);
D. printf("%d\n", pr1->ldpoint.x);