I often think of the days _____ I stayed with the experts, _____ has a great effect on my job.

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

 I often think of the days _____ I stayed with the experts, _____ has a great effect on my job.

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

I often think of the days _____ I stayed with the experts, _____ has a great effect on my job.

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

I often think of the days _____ I stayed with the experts, _____ has a great effect on my job.

I often think of the days _____ I stayed with the experts, _____ has a great effect on my job.