Final answer:
A do-it-yourself carwash with five washing bays is categorized as a multiple server, single phase queuing system, with five bays serving as individual servers and the car wash process being the single phase of service.
Step-by-step explanation:
A do-it-yourself carwash with five washing bays would be a multiple server, single phase queuing system. In a multiple server system, there are several servers available for customers to use, which in this case are the five washing bays. Given that the car wash process consists of only one type of transaction or activity, which is the act of washing the car itself, it's referred to as single phase. There is no indication of a secondary process; hence, 'two phase' would be incorrect.