选C ,用one 来指代前文出现过的名词a new life
A,what不能引导定语从句
B,that 不能引导非限定定语从句,注意前面有逗号,这里如果有选项which 也可以选,引导非限定定语从句.
For me traveling to Antarctica proved to be the beginning of a new life,which I had thought I would never see.
D,it 也可以表指代,但不可以用在句中这样的情况,如果要用it,句子应该是For me traveling to Antarctica proved to be the beginning of a new life,but I had thought I would never see it.
句意：对我来说,去南极旅行就是一种新生活的开始,但我从来没想过我能看到这种新生活的开始.