Does the type of movie that children are watching make a dif…

Does the type of movie that children are watching make a difference in the amount of snacks they will eat?  Seventy-five randomly selected children were randomly assigned to watch either a cartoon, a science fiction, or a live action musical (25 to each). Cheese crackers were available in a bowl, and the investigators compared the number of crackers eaten by children while watching different kinds of movies. What are the response variable and the explantory variable in this study?