6-7. Three mutually exclusive design alternatives are being considered. The estimated cash flows for each alternative are given next. The MARR is 20% per year. At the conclusion of the useful life, the investment will be sold. A B C Investment cost $28,000 $55,000 $40,000 Annual expenses $15,000 $13,000 $22,000 Market value 26.4% Annual revenues Useful life IRR 10 years 10 years 10 years $23,000 $28,000 $32,000 $6,000 $8,000 $10,000 24.7% 22.4%