5-72 Consider the following four alternatives. Three are "do something" and one is "do nothing." AB Cost 0 50 30 40 Net annual benefit 0 12 4.5 Useful life, in years 5 10 10 At the end of the 5-year useful life of B, a replace- ment is not made. If a 10-year analysis period and a 10% interest rate are selected, which is the preferred alternative