For each day of the week that Tanya is good, she earns a fake dollar from her teacher. By the end of every week, Tanya has the option of using her dollars to buy something from the school store or saving them to buy something at a later time. The issue of fake dollars in response to good behavior is an example of

• A. primary reinforcement.
• B. behavior modification.
• C. classical conditioning.
• D. placebo learning.