It is so difficult a question_______ none of the kids could work it out.

    A. as          B. that         C. which         D. X

It is so difficult a question_______ none of the kids could work it out.

1. A.
   as
2. B.
   that
3. C.
   which
4. D.
   X

It is so difficult a question_______ none of the kids could work it out.