At the start of the game, there is a 2:3 chance that Jennifer will pick a door with a goat behind it. If she does, the host will reveal the other other goat, and switching doors will get Jennifer the car.
I think I get the answer, but I'm a little unclear about this point. I didn't see anything in the question stating that the host will always start by opening a dorr that Jennifer didn't select. If she got it wrong, perhaps the host would have just said, "too bad, you picked a goat." If that's true, the answer is obviously that she has to stick with the same door. I would think that this assumption should be written into the question, but maybe I'm misunderstanding something here.