The police were trying to _____ where the drug dealers were _____ it suddenly dawned upon them that they might be hidden somewhere 10 miles within the border between the two countries

1. A.
   come out; when
2. B.
   make out; while
3. C.
   figure out; when
4. D.
   think out; since

The police were trying to _____ where the drug dealers were _____ it suddenly dawned upon them that they might be hidden somewhere 10 miles within the border between the two countries.

A. come out; when 　B. make out; while 　 C. figure out; when　 D. think out; since