The Major Dependent Measurement Recorded of Subjects' Behavior That Was

The major dependent measurement recorded of subjects' behavior that was used as the basis for analyzing the results of Dickerson et al.'s water conservation experiment was:

A) the attitudes the subjects held about the value of water conservation.
B) the degree to which subjects agreed with statements such as "I always turn off the water when soaping up."
C) whether or not subjects were willing to sign a petition that advocated water conservation.
D) how long subjects ran the water during their showers.