In Designing a General Service Facility, Capacity Should Be Such

In designing a general service facility, capacity should be such that the target rate of service utilization (ρ) , in order to get the best general purpose design, should be

A) less than 0.6 (or 60%) , so that your system would be within the zone of service with maximum possible utilization within that.
B) more than 0.6 (or 60%) so that your system would have a good utilization
C) about 0.7 (70%) so that your system would be in the zone of service with maximum possible utilization within that.
D) more than 1.0 (100%) so that the servers are fully utilized, even if the customers had to wait a little
E) between 0.9 (90%) and 1.0 (100%) so that the utilization of the system is ideal.