The answer is the color of the room
Step-by-step explanation:
In this study, the color of the room is the factor or variable that is modified by the researcher. Also, it is expected the color of the room affects participants' behavior but not the opposite. This shows the color of the room is an independent variable because this factor is not affected by other variables, and it modifies the dependent variable (behavior). Moreover, in studies, the independent variable is always the one that is changed by the researcher.