A group of researchers wanted to determine if people will eat more food in a room with red paint than in a room that is decorated blue. Half the participants in this study ate in a red room and half ate in a blue room. The researchers then measured how much food was consumed in each of the two rooms. In this study, the independent variable was

a. the type of food that was available during the study.
b. the amount of food that was consumed.
c. the color of the room.
d. how hungry the participants were at the end of the study.

C