Question

stimulus or event that increases the probability that the response it follows will be repeated
o stressor
o melatonin
o stimuli
o reinforcer
o percept

Explanation:

In psychology, a reinforcer is a stimulus or event that increases the likelihood of a response being repeated. A stressor causes stress, melatonin is a hormone related to sleep - wake cycles, stimuli are general sensory inputs, and a percept is a result of perception.

Answer:

D. reinforcer