Afecreen inc. has an average of 85 working days in a quarter. the company conducts quality checks to assess the performance of its employees. the employees who perform well may receive a bonus after 70 days or 100 days, but the average interval between the completion of tasks and the receiving of bonus is 85 days. in the context of reinforcement theory of motivation, which of the following intermittent reinforcement schedules does this scenario best illustrate?

a. a fixed interval reinforcement schedule
b. a fixed ratio reinforcement schedule
c. a variable interval reinforcement schedule
d. a variable ratio reinforcement schedule