The correct answer is A.
A token economy is based on operant conditioning principles and consists on the reinforcement of a specific target behaviour. It can be applied both in scenarios with adults and children.
A token is an object that has no intrinsic value but that can be used as a reinforcer because it can be exchanged for privileges according to a set of pre-established rules. For example the token could be a voucher that allows the student who has stood in silence during the lesson to eat a snack in class.
