Designers need to design how to continue the air in a new building with a 40-year life. Four alternatives are available, both of which have 20-year lives. Costs are given below. Use 12% interest rate. A B C D First Cost 90,000 60,000 85,000 72,000 SV in 20 years 10,000 8,000 12,000 9,000 Ann. Fuel Cost 3,000 5,000 4,500 3,500 Ann. Maint. Cost 2,200 3,200 1,800 2,400 Tax (%) of FC 3% 1.5% 2.3% 1.7% a. What is the present worth of alternative D?(10 points) b. What is the ROR of Alternative A?(10 points) c. Which is the best alternative? Use ROR on additional investment.(20points)