It's a stupid question to begin with. It obviously would depend on the individual person, and with bodybuilders you need to be more specific...for example, are you referring to their bodyfat % on contest day or their average bodyfat % throughout the year? Also, any athlete can get fat in the "offseason", marathon runners included. Alot of marathon runners and swimmers eat a ton of calories, primarily from carbs for energy, and really aren't that lean. Then again, you have alot of Kenyan guys who are probably in the low single digits. I would argue that the average sprinter is actually leaner than the average marathon runner. If I had been given this question, I would probably have picked basketball player (assuming average bodyfat % throughout the year, as the question did not specify).