The PLA soldiers came to the ruins of Yushu and after ______ seemed to be a long time, they helped some victims out.

The PLA soldiers came to the ruins of Yushu and after ______ seemed to be a long time, they helped some victims out.

1. A.
   which
2. B.
   that
3. C.
   what
4. D.
   when

 The PLA soldiers came to the ruins of Yushu and after ______ seemed to be a long time, they helped some victims out.

  A. which          B. that          C. what           D. when

The PLA soldiers came to the ruins of Yushu and after ______ seemed to be a long time, they helped some victims out.