Final answer:
The longer the delay between the SD (discriminative stimulus) and the unconditioned reinforcement on a chain schedule of reinforcement, the weaker the chain becomes, as it reduces the effectiveness of the reinforcement strategy in operant conditioning.
Step-by-step explanation:
On a chain schedule of reinforcement, the longer the delay between the SD (discriminative stimulus) and the unconditioned reinforcement, B) The weaker the chain becomes. This is because the connection between the behavior and the reinforcement is less clear or immediate, which can reduce the effectiveness of the reinforcement. A shorter delay between the discriminative stimulus and the reinforcement generally results in a stronger connection and thus a more effective reinforcement strategy. Understanding these dynamics is critical in operant conditioning, where the goal is to influence behaviors through reinforcements.