In an Experiment, Two Groups of College Students Were Shown

Multiple Choice

In an experiment, two groups of college students were shown the same pictures of 25 women from a different campus. However, for one group, the photos were altered to make the faces in the photographs appear more symmetrical. Participates rated the attractiveness of the women on a one to ten scale with ten being very attractive and one be very unattractive. In this experiment, which variable is most likely a control variable?

A) whether or not the photographs where symmetrical
B) the one to ten attractiveness rating scales
C) the sex of the person in the pictures
D) whether or not the subjects were college students