After designing more experiments,they were able to clarify the procedure　　  bees communicate information that they use to find and fetch food.

A.by which　　　　　　　　　B.in which

C.by that　　　　　　　　　　D.for which

After designing more experiments,they were able to clarify the procedure　　 bees communicate information that they use to find and fetch food.

1. A.
   by which
2. B.
   in which
3. C.
   by that
4. D.
   for which