请帮我回答一道英语题,并说明理由!

问题描述:

请帮我回答一道英语题,并说明理由!
He asked me ( ) during the summer holidays?
A.where had I been B.where I was C.where I had been D.where was I
标准答案是选择c,求理由!

宾语从句要用陈述语序,发生在过去之前故用过去完成时态