If nature does not provide man with the necessary material,it is the laboratory ____ he will turn to for it．\x05 \x05A．where\x05B．that\x05C．which\x05D．what 为什么不选C,

If nature does not provide man with the necessary material,it is the laboratory ____ he will turn to for it．\x05 \x05A．where\x05B．that\x05C．which\x05D．what 为什么不选C,
If nature does not provide man with the necessary material,it is the laboratory ____ he will turn to for it．\x05
\x05A．where\x05B．that\x05C．which\x05D．what
为什么不选C,

If nature does not provide man with the necessary material,it is the laboratory ____ he will turn to for it．\x05 \x05A．where\x05B．that\x05C．which\x05D．what 为什么不选C,
这是强调句!
这样跟你讲,首先你需要知道强调句是什么.
举个例子:
the pretty girl moved in the hotel with a playboy.
强调主语部分：it was the pretty girl that moved in the hotel with the playboy.
强调宾语hotel:it was the hotel that the pretty girl moved in with the playboy.
强调宾语playboy:it was the plaboy that the pretty girl moved in the hotel with.
强调句可以强调句子中除谓语以外的任何句子成分.
你所说的那个句子可以用which,但需要改成定于从句.
如下：
if nature dose not provide men with the necessary material,the lab to which he will turn for it can be useful.

which做代名词，代表前一指定名词laboratory，但此题最后已经加了it，再使用which就多余了。个人见解。

我还真不知道