be pointed后可接at或to或out

有一读者问： 有这样一道选择题：

He_______________by all mothers as an example of what a son should be.

A. pointed to　B. was pointed to

C. pointed at　D. was pointed at

正确答案是D，为什么不是B呢？

不知命题人如此命题的理由如何，我们则认为这里既可用was pointed at，亦可用was pointed to，还可用was pointed out。