The common measures of a queuing system's performance include: a. Utilization, average queue length, probability that the waiting time will exceed a specified duration b. Average time each customer spends in the system, utilization, average time each customer spends in the queue c. Average queue length, maximum time a customer may spend in the queue, the utilization d. Average time each customer spends in the system, maximum queue length, maximum time a customer may spend in the queue