请解释下答案，并帮我分析下从句中的句子成分，谢谢

Question

Many workers were organized to clear away ______remained of the World Trade Center.
A. those B. that C. what D. where

Answer 1

what引导的从句做宾语。这是名词性从句的考察。很简单，主句clear away缺少宾语，后面从句缺少主语，中间用what连
He didn't get what he wanted.
I will tell you what I know.
This is what I bought yesterday.
就是说主句缺少主语，宾语或者表语，从句也是这样，中间用what.

Answer 2

选A。主语Many workers 谓语were organized 目的状语to clear away ______ 后置定语remained of the World Trade Center.追问

不对，正确答案是C

Answer 3

主语Many workers 谓语were organized 目的状语to clear away __what（宾语）remained of the world Trade Center__ .