The correct answer is C. Ravi is given a candy by his mother for cleaning his shoes.
Step-by-step explanation:
In psychology, positive reinforcement refers to rewarding an individual after he or she does something that is considered as "positive" or "desirable". Additionally, positive reinforcement motivates the individual to perform a certain action more often.
According to this, the example of positive reinforcement is "Ravi is given a candy by his mother for cleaning his shoes" because the candy acts as a rewarding that is given after a positive action (cleaning his shoes), also, the candy motivates Ravi to clean his shoes more often.