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I think number 2 is the easiest to work with, but it is way too broad. Also the term "leadership skills" doesn't scream diversity. You are definitely right about that lending itself more to a greatest strength essay. A better angle might be to focus on the ability to identify a serious health issue, the initiative to start something, and the drive to produce something that didn't exist before. I'd drop the board member of a pre-med club. List that in your activities section.
It is a weak, 'diversity' topic, the creative problem solver, but can be made into a very good essay, but with what you have listed, I think that is your best option. You can try to spin yourself as being an action > words person. That definitely fits the ideological diversity bill. While many will think it, few actually are that way. If you have a good experience bank to pull from I think you can pull it off.