I also had a hard time picking between another snapshot and no backup. I did have one thought in favor of the answer specified though (although I thought about it after answering the question). Taking another snapshot could destroy the purpose of having the snapshot in the first place. I mean, if you're taking a snapshot to capture a specific point in time, taking another snapshot would cause you to lose that 'bookmark'. I guess I'm also assuming that if the growth is what you are worried about you wouldn't keep the old snapshot around after creating a new one.

Don't get too wrapped up in the QOD. If you're more worried about the points and percentage than learning and taking a shot, there are a several ways to make sure you get them all right.