选C.
“no matter＋疑问词”或“带后缀ever的疑问词”可以表示“不管……”的含义,
引导让步状语从句(前一结构所表示的语气要稍强于后一结构),
例如：However (= No matter how) much I tried,I failed to work out the maths problem.
无论怎么努力,我还是解不出这道数学题.
// However (=No matter how) hard he may try,he will not attain his goal.
无论怎样努力,他都达不到他的目标.
// Whatever (=No matter what) you say,I will not change my mind.
无论你说什么,我也绝不改变主意.//
Whenever (=No matter when) you come,you will be warmly welcomed.
不论什么时候来,你都会受到热烈欢迎.//
Wherever (=No matter where) you go,you will find the same thing.
无论到哪里,你都会发现同样的事情.//
Whoever (=No matter who) you are,you have no right to do such a thing.
不管你是谁,你都无权做这种事.