The provided text explicitly states that a preference assessment only identifies what a client likes or prefers not what will necessarily function as a reinforcer to increase behavior The effectiveness of a token economy is directly tied to the power of its backup reinforcers Therefore the most critical next step after selecting backup stimuli is to conduct a reinforcer assessment or at least functional testing to empirically determine if these preferred items actually increase the likelihood of target behaviors The text emphasizes this by stating tokens are only as powerful as their backup reinforcers and Marthur needs to follow up this preference assessment take these backup stimuli and identify what are and arent reinforcing While pairing tokens with praise option D is a valuable strategy for establishing praise as a Generalized Conditioned Reinforcer GCR it is secondary to ensuring the foundational elements of the token economy the backup items are indeed reinforcing Including a response cost option A is not mandatory and is a punishment procedure and implementing a general punishment procedure option B is unnecessary and not inherent to the positive reinforcement system of a token economy