Token reinforcement systems require what two components to be effective?

The correct answer is C. Tokens and backup reinforcers.

Token reinforcement systems are strategies used in behavior modification where tokens are earned for demonstrating desired behaviors. These tokens can later be exchanged for backup reinforcers, which are tangible rewards or privileges. This system encourages positive behavior by providing immediate reinforcement (the tokens) for good behavior that can be accrued toward a more substantial reward.

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