It was not her business, she decided, to ask ________ the money

It was not her business, she decided, to ask ________ the money came from.
A、how
B、where
C、why
D、when
【正确答案】：B
【题目解析】：此句话的意思是她认为自己没有必要询问钱的来源。“come from”表示来自...,根据句意可知，“where does/do sth come from”固定句型，“where”在此引导一个宾语从句。