Sentence Correction

While depressed property values can hurt some large investors, they are potentially devastating for homeowners whose equity-in many cases representing a life's savings-can plunge or even disappear.

a. same
b. they can potentially devastate homeowners in that their
c for home owners they are potentially devastating, because their
d. for homeowners, it is potentially devastating in that their
e. it can potentially devastate homewoner5s, whose

QA is A

I can see that B and D are out because it says "in that their" not good
E - "IT" refers to the equity - definitely wrong also redundant
a b confuse me because they all have "they" and it looks like they can refer to investors or values. I know my reasoning is wrong but cant seem to reason why A is right when the "THEY" is ambiguous.

This type of problem is my biggest hurdle in SC. How can I learn this best and where can i go to get some good lessons on this type of topic.

please help with detailed answer so i can finally grasp this!