Five mutually exclusive alternatives are being considered for providing a sewage-treatment facility. The annual equivalent costs and estimated benefits of the alternatives are as follows:

Which plan, if any, should be adopted if the Sewage Authority wishes to invest if, and only if, the B€“C ratio is at least 1.0.?

Annual Equivalent (in thousands) Alternative Benefits Cost $1,050 $1,110 900 810 1,230 1,350 1,390 1,500 1,140 990