Final answer:
Franklin receives a reinforcer after every 4 responses on an FR4 schedule of reinforcement.
Step-by-step explanation:
The student is asking about a specific schedule of reinforcement within the context of operant conditioning, a concept in psychology. Franklin is on an FR4 schedule of reinforcement for correctly responding to the cue "roll car". In a fixed ratio reinforcement schedule, reinforcement is delivered after a predictable number of responses. For an FR4 schedule, Franklin would receive a reinforcer after every 4 responses. So, the correct answer to the student's question is: d. After every 4 responses.