Now there is a system ______ the waste is disposed of using the principles of ecology.

A：though

B：which

C：of which

D：whose

A：which, range to, between

B：whose, range from, to

C：that, range for, and

D：it, range with, to

A：them; when

B：which; that

C：what; that

D：which; when

A：where

B：which

C：its

D：whose

A：who

B：whom

C：them

D：those

A：what

B：when

C：that

D：where

A：which I think is

B：which I think it is

C：which I think it

D：I think which is

A：the hands of whom

B：whom the hands of

C：which the hands of

D：the hands of which

A：that; have seen

B：that; saw

C：which; have seen

D：which; saw

A：that

B：where

C：how

D：when