英语选择,请解析~

A 要加to

把句子还原后，考查的短语其实是(the)answer to... ...的答案

The child asked questions to which only a doctor could answer.

B 这里是个从句， which指代 the question， 如果你不清楚，可以把句子还原成两个：
1. the child asked the question
2. only a doctor could answer that question

很显然 which 指代了that question
不用 to

B
question to 某人，表示向某人提问

后面是从句，这里直接用which就可以

意思是“这个孩子的问题只有医生能回答”

A啊老大，这个是个定语从句，原本应该是the child asked questions which only a doctor could answer to.但是为了简化，直接把to提到which 之前了，英语里面有很多这种情况，from,in之类的介词如果在句末一般来说都需要提前到which之前

A
answer to question是一固定搭配
又因此句是一从句所以选A

A
answer后要有介词to，to前提变成to which