A Government Agency Is Having Problems with Personal Telephone Calls

A government agency is having problems with personal telephone calls made during working hours.Because each minute of a personal call costs the agency $0.50 in wasted wages,it has decided to hire operators to monitor calls.The agency wants to hire the number of operators that will minimize the total cost of personal calls. $\begin{array}{c}\begin{array}{c}\text {Number of}\\\text { operators}\\0\\1\\2\\3\\4\\5\\\end{array}\begin{array}{c}\text {Minutes of personal}\\\text { calls(per week) }\\3900\\2300\\1300\\600\\100\\0\\\end{array}\end{array}$
Based on the above information,what is the most the agency would be willing to pay the fifth operator?

A) $100
B) $200
C) $400
D) $500
E) none of the above