10-11. 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: Annual Equivalent (in thousands) Alternative Cost Benefits A $1,050 $1,110 B 900 810 C 1,230 1,390 D 1,350 1,500 E 990 1,140 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.? (10.9)