-What are you doing here?
-Oh,I work here now.
-_____________
A.For what?    B.So what?
C.What for?    D.What's up?

第一个

C是最地道的。

B
-（不满的）你怎么到这里来了
-哦，我现在是公司职员了
-那又如何？（职员也不能随便进经理办公室啊）

回复：5楼
选D的话，把第二句改成Oh,I'm looking for you就顺了，后面的What's up?就是找我有什么事，表示问候的话……用在这里太突兀了

回复：7楼
问人为什么在这里工作，不也是很突兀吗

What a pointless, out-of-context, virtual half-conversation for a question.... the answer could be any of the above, depending on the relationship between the two speakers, and the situation in which they find themselves.
However, it looks to me whoever set this question is looking to extend the question along the lines of :
"So what sort of job do you do here?"
Possibly A or C - who knows how these illogical minds think?

-What are you doing here?
这样问是很不礼貌的，或者说是有挑衅性的。
我在这儿干什么，你没有长眼睛还是装作看不见？
-Oh,I work here now.
被问的人显然地位低下，被质问也没有脾气，只能低三下四地oh一声，小心翼翼地解释：“现在，我到这里上班了”。
-_so what?____________
问话的人依然趾高气扬：“你到这里上班了又能怎么样呢？”


C

说了这么多，看来大家的意见还是不一样呀