The government is considering five mutually exclusive proposals for the improvement of the postal service. The annual equivalent costs and estimated benefits of alternatives are as follows:

Which proposal, if any, should be adopted if the postal department wishes to invest if, and only if, the B-C ratiois at least 1?

Annual Equivalent ($) Alternative Costs Benefits $1,200 $1,000 $2,000 $2,400 $2,600 $2,800 $4,000 $4,500 $5,000 $5,000