Answer:
I'm pretty sure it's a. With refrigeration you do have more food variety, the food lasts longer so less waste.
The control group outs the one that you don't change. The reason you don't change it is because you use it as a comparison with the other groups.
So to sum up, when matter is transitioning from solid to liquid (melting) or liquid to solid (freezing<span>), its </span>temperature<span> is fixed at the </span>melting/freezing<span> point, which is the </span><span>same temperature</span>