Why is the allusion to Bluebeard's Castle appropriate?

because Rochester is also unattractive

because Rochester also has a wife hidden in a room

because Jane really does want the security of Rochester's money and large home because Jane is not obedient

The best choice here is the second one, because Rochester also has a wife hidden in a room. If you're familiar with Bluebeard, then you'll remember that he has a room that hides all of his former wives. When she discovers that room, she is horrified, understandably. While Rochester is not hiding a multitude of wives and only the one, the allusion is apt here because Rochester is hiding her from the public.

Because of this, the other choices don't make much sense. We have no way of knowing if Rochester is unattractive overall. We just know that Jane finds him attractive, though that could simply because of his money. The third choice doesn't make much sense because if Jane wanted to be with Rochester she would not have fled from him. And, this doesn't have anything to do with Bluebeard. The fourth choice is similar to this because Jane is quite obedient and, again, has nothing to do with Bluebeard.