Answer: C. Increases
Explanation: If the reinforcement i.e stimulus achieves the desired response i.e a response to a given stimulus, that is, the positive outcome as it is said, then it is likely that this response will be repeated / occurring again and that probability increases. Whether it is a positive or negative reinforcement, that is, whether a trait or habit wants to be potentiated or wants to be eliminated, with reinforcement an adequate response to the stimulus occurs, and it is likely that this response will be repeated because reinforcement in the form of a stimulus aims to increase the response.