In an experiment, a researcher showed children a video of a person interacting with a doll. Half of the children watched a video of a person behaving violently toward a doll, and the other half saw a video of a person playing nicely with a doll. The researcher also looked at whether the gender and age of the child made a difference in how they interacted with the doll. In this study, the dependent variable was
A. the age at which children begin engaging in parallel play
B. the gender of the researcher
C. the gender of the children
D. the way children interact with a doll
E. watching a video in which a person exhibits violent behavior toward a doll or plays nicely with a doll