答：C
I will answer for it that Tom can asnswer for his fault.
译：我保证汤姆能为他的错误负责.
析：本题考查aswer for的两种不同用法：
a.[为…事][对人]负责[to][for]
He will have to for his wrongdoing one day.
他终有一天会为他所犯的罪负责
b.[为人品、品质等] 负责,[为…]保证[for]
I can't for his honesty.
我不能保证他是诚实的
I'll answer for it that the next one will be better .
我保证下一个会更好.
原句和最后一个例句一样,用到了形式宾语it,真正的宾语是that从句.
第一个answer for sth.是b用法.意为“保证,为某件事性担保”
第二个answer for sth.是a用法,表示”为.负责“