The question ______ we can get enough coal for the winter has not been cleared up yet.

A.that               B.if            C.which              D.whether

The question _______ we can get enough coal for the winter has not been cleared up yet．

1. A.
   that
2. B.
   if
3. C.
   which
4. D.
   whether

The question _______ we can get enough coal for the winter has not been cleared up yet .

  A. that    B. if   C. which   D. whether