Due to poaching and increased cultivation in their native habitats, re

It is absolutely the case that poaching and increased cultivation have caused researchers to determine something

The act of poaching in my view CAN CAUSE researchers to determine that there are fewer than 100 leopards.

Just like - The act of poaching can CAUSE researchers to estimate that there are fewer than 500 free rhinos

Here's how I'd think about it: the moment I see "their," I'm asking myself two questions: 1) is there a plural noun the pronoun can refer to? and 2) does this plural noun make sense?

It's true that if my eyes drift backwards from "their" I might first come across "researchers" as a candidate. But while "researchers" is plural, it makes absolutely no sense. We're talking about something getting poached -- common sense tells me that we're probably referring to some kind of animal here, not researchers. (Though I definitely worked with some researchers in my PhD program who reminded me of wild animals. )

Also, the phrase "native habitats" is another clue that we're talking about an animal, not people. So I'll keep looking for my antecedent elsewhere.

As soon as my eyes begin to move in the other direction, they come across "leopards." Well, this is plural. And it's perfectly logical to write about leopards getting poached in their natural habitats. So I'm pretty confident that "their" refers to "leopards." There's no rule about where to look for the pronoun's antecedent. I just knew I was looking for something plural and logical. "Leopards" is the only thing that works.

Do I love this? Nope. But I don't have to. There's no rule that if a sentence contains a plural pronoun, it must contain just one plural noun elsewhere in the sentence. It just needs to have something that could work logically. Every other answer choice here contains a concrete error, so I'm left with option (E).

I hope that helps!