Q17:

A study by the Ocean Wildlife Campaign urged states to undertake a number of remedies to reverse a decline in the shark population, which includes the establishment of size limits for shark catches, closing state waters for shark fishing during pupping season, and requiring commercial fishers to have federal shark permits.

1. which includes the establishment of size limits for shark catches, closing
2. which includes establishing limits to the size of sharks that can be caught, closing
3. which include the establishment of size limits for shark catches, the closing of
4. including establishing size limits for shark catches, closing
5. including the establishing of limits to the size of sharks that are caught, the closing of

答案是D

不明白为什么是D而不是B

B也完全符合平行结构，establishing, closing and requiring

which指代前面的remedies也没有问题吧

不说单复数问题

which和ing在这道题中有对错的区别么？

如果which修饰remedies有歧义的话为什么ing修饰没有？