The prices of houses ______ because the demand of them become more and more great.

1. A.
   are rising
2. B.
   rise
3. C.
   had risen
4. D.
   have been risen

The prices of houses ______ because the demand of them become more and more great.

         A. are rising               B. rise                                   C. had risen               D. have been risen

The prices of houses ______ because the demand of them become more and more great.

       A. are rising          B. rise                          C. had risen           D. have been risen

The prices of houses ______ because the demand of them become more and more great.