( )fred solved the problem is not clear to us

( )fred solved the problem is not clear to us
答案是what 我就搞不懂了,solved前面有主语fred后面有宾语the problem,那为什么还是选what?
不好意思啊,有4个选择,A,IF B.THAT.C.HOW.D.WHAT.重新选一下把...