The discovery of these tombs is _______ for scholars’ studying the history of the Tang Dynasty.

1. A.
   of very important
2. B.
   great importance
3. C.
   of great significance
4. D.
   great significant

The discovery of these tombs is _______ for scholars’ studying the history of the Tang Dynasty.

A. of very important         B. great importance

C. of great significance       D. great significant