An Animal Trainer Is Trying to Teach a Lion to Perform

An animal trainer is trying to teach a lion to perform tricks for the circus.First,the lion is given food if he sits quietly on a chair.Next,the lion is given food if he raises one paw.Finally,the lion is given food if he gives the trainer a "high-five." In this example,the lion is being trained by

A) negative reinforcement.
B) generalization.
C) punishment.
D) shaping.