In the park there are benches,___ you can enjoy a good rest there. A Which B On which C .where

In the park there are benches,___ you can enjoy a good rest there. A Which B On which C .where D.and

B on which
公园上的长条椅是供人坐的
一般来讲是sit on a（the）chair。 当然 sit in a （the） chair 是坐在椅子里(陷在椅子中间）
再看这句话：
原来是两句：There are benches in the park。和 You can enjoy a good rest there on the benches
现在我们合成一句：there are benches in the park， on which（the benches) you can enjoy a good rest there.
把前一句倒桩：in the park there are benches , on which you can enjoy a good rest there.

B,非限制性定语从句

上面这位已经很详细了。推荐。支持他、。！
补充一下。非限定性定语从句。