I would say C but I’m not quite sure
It help conserve energy so that in summer they can stay healthy. Also alows them to eat a buch of food and it not be so much
Don't quote me on it but I believe the first one was Democritus in the time of Ancient Greece. At the time he had no evidence though, just a lucky guess made by him.
Prior knowledge allows you to make a well-informed hypotheses and a better-planned experiement.