MM$?$ has a queuing problem where customers who line up to pay their selections form the waiting line. The MM$2$ system consists of an arrival rate o $24$ per hour according to a Poison distribution, and service times are on average equal to $2$ minutes per customer.What is the number of customers waiting in the queue on average?O a$.3\mathrm{.}2$O b$.1\mathrm{.}667$O c$.40$ d$.0\mathrm{.}152$