Final answer:
Exclusionary time-out in behavior modification has risks of aggression and incidental reinforcement.
Step-by-step explanation:
Exclusionary time-out is a technique used in behavior modification with children. It involves removing a child from a desirable activity to decrease unwanted behavior. One risk associated with exclusionary time-out is aggression. When a child is excluded from an activity, they may become frustrated and act out in aggressive ways. Another risk is incidental reinforcement. If a child enjoys being alone or gets attention from peers after being put in time-out, they may associate the time-out with positive outcomes and the behavior may be unintentionally reinforced. Therefore, the correct answer is C. both A and B.