请教GWD-8-Q11

以下是GWD中的一道语法题，答案为A。但A中用their合理吗？

GWD-8-Q11:

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.

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

我查過字典 裡頭寫著fish有兩種複數形式: fish和fishes,但以fish為較常見普通的形式

http://forum.chasedream.com/dispbbs.asp?BoardID=23&replyID=3053536&id=339768&skin=0

可以看看这贴