GWD21-5:legal limits for fish，请NN们解释一下为什么选C啊，偶觉得A也对吧……谢谢先了！

There are no legal
limits, as there are for cod and haddock, on the size of monkfish that can be
caught, a circumstance that contributes to their depletion through overfishing.

A.      
There are no legal limits, as there are for cod and
haddock, on the size of monkfish that can be caught, a circumstance that
contributes to their depletion through overfishing.

B.      
There are no legal limits on the size of monkfish that
can be caught, unlike cod or haddock, a circumstance that contributes to
depleting them because they are being overfished.

C.      
There are legal limits on the size of cod and haddock
that can be caught, but not for monkfish, which contributes to its depletion
through overfishing.

D.      
Unlike cod and haddock, there are no legal size limits on
catching monkfish, which contributes to its depletion by being overfished.  (A)

Unlike catching cod and haddock, there are no legal size limits on
catching monkfish, contributing to their depletion because they are overfished.

I choose D

C is not correct. "which" can not stand for the whole sentence before it in GMAT.

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