Another driver had just driven into the back of Jack's car ______ he was waiting at some traffic lights.

1. A.
   since
2. B.
   once
3. C.
   while
4. D.
   during

Another driver had just driven into the back of Jack's car ______ he was waiting at some traffic lights.

A. since B. once   C. while        D. during 

Another driver had just driven into the back of Jack's car ______ he was waiting at some traffic lights.

A. since  B. once  C. while  D. during