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 hires operators to monitor calls in order to attain the optimal number of personal calls (minimize total cost of personal calls) . $$\begin{array} { c c } & \text { Total minutes af }\\\text { Numbe of } & \text { personal calls (per } \\\text { Operators } & \text { hour) } \\\hline 0 & 600 \\1 & 480 \\2 & 410 \\3 & 370 \\4 & 350 \\\hline\end{array}$$ Based on the above information,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