I often think of the days ______ I took part in the military training with the soldiers, _____ has a great effect on my studies.

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

I often think of the days ______ I took part in the military training with the soldiers, _____ has a great effect on my studies.

A. which; that   B. that; which   C. when; who  D. when; which