Final answer:
The professor's praise is a positive reinforcer that increases the likelihood of Shondra asking questions in class.
Step-by-step explanation:
In the example provided, the professor's praise is a positive reinforcer. Positive reinforcement refers to the addition of a desirable stimulus to increase a behavior. In this case, the professor's praise serves as a positive reinforcer, as it increases the likelihood of Shondra asking questions in class in the future.