Reya is a neuroscientist who studies behaviors in mice. She is working on a project in which the mice are given a snack when they push a small button on the wall of their enclosure. At first, the mice don't understand the connection between thebutton and the snack. In time, they leam to push the button whenever they want a snack. Reya's experiment an example of what type of conditioning?
A. operant
B. classical
C. magical
D. phantom