Fidan Is Studying a Model of Obesity

Fidan is studying a model of obesity. For her experiment, Fidan uses three groups of 31 rats each that are given either (1) 24-hour access to high calorie treat food in addition to their normal chow, (2) restricted 8-hour access to high calorie treat food and 24-hour access to their normal chow, or (3) 24-hour access to only their normal chow. Every day, Fidan weighs the animals and carefully takes note of the amount and type of food each animal has consumed. At the end of the experiment, Fidan performs surgery on all the animals and notices that the animals that put on the most weight showed noticeable differences in their hypothalamus compared to the rest of the rats.
-Which is the control group in Fidan's experiment

A) The rats that had 24-hour access to both high calorie treat food and their normal chow.
B) The rats that had restricted access to high calorie treat food and unlimited access to their normal chow.
C) The rats that had unlimited access only to their normal chow.
D) There was no control group.