C
二者的区别在于意思不一样
who指谁,是特殊疑问词
例如：who are you?
whoever是“无论谁”,引导主语从句,有时也引导宾语从句,类似的有“which”与“whichever”
whoever (pron). 谁
⑴连接代词,引导名词性从句(=anybody that)
Whoever comes will be welcome. 谁来都欢迎.
Give it to whoever you like. 你喜欢给谁就给谁.
⑵做疑问代词(比who语气重) Whoever said that? 是谁讲的那话?
Whoever can that be knocking at the door? 敲门的会是谁呢? conj. 不管是谁(引导状语从句,=no matter who)
Whoever rings, tell him I'm out. 不管谁来电话,告诉他我不在家.