An Agency Is Having Problems with Personal Phone Calls Made

An agency is having problems with personal phone calls made during working hours. Each minute of a personal call costs the agency $0.50 in wasted wages. The agency decides to hire operators to monitor calls in order to attain the optimal number of personal calls (minimize total cost of personal calls) .

$$\begin{array} { c c } \text { Number of } & \text { Total minutes af } \\\text { Operatars } & \text { personal calls (per hour } \\\hline 0 & 60 0\\1 & 480 \\2 & 410 \\3 & 370 \\4 & 350\end{array}$$
-What is the most the agency would be willing to pay the first operator?

A) $480
B) $300
C) $240
D) $120
E) none of the above