An entrepreneur offers services that can be modeled as an s-server Erlang loss (Erlang-B) system. Suppose the arrival rate is 4 customers per hour; the average service time is 1 hour; the entrepreneur earns $ 2.50 for each customer served; and the entrepreneurs operating cost is $1.00 per server per hour (whether the server is busy or idle).

A. The optimal number of servers, from the entrepreneur's point of view:

B. if the entrepreneur deploys the optimal number of servers, he/she should expect to make a profit of $ per hour:

C.the maximum number of servers beyond which it is unprofitable for the entrepreneur to remain in business is: