一题语法题，举手请教nn

Q5: (這題实在不能理解，C答案中的which不是要指代最近的单词吗？
                可是 monkfish怎么能够产生depletion呢？)

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.

1. 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.
2. 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.
3. 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.
4. Unlike cod and haddock, there are no legal size limits on catching monkfish, which contributes to its depletion by being overfished.
5. Unlike catching cod and haddock, there are no legal size limits on catching monkfish, contributing to their depletion because they are overfished.

  這題比较费解，在A和C中百转千回。大牛们来吧！