_______ the rain falling so hard, it becomes more and more difficult to carry on the rescue work.

_______ the rain falling so hard, it becomes more and more difficult to carry on the rescue work.

1. A.
   Since
2. B.
   As
3. C.
   With
4. D.
   For

_______ the rain falling so hard, it becomes more and more difficult to carry on the rescue work.

A. Since            B. As           C. With             D. For

_______ the rain falling so hard, it becomes more and more difficult to carry on the rescue work.