An old machine that originally cost $9,500 thus far has accumulated depreciation of $1,900. The remaining useful life is four years, with no salvage value at the end of its useful life. A new machine is now available that costs $8,500, with a useful life of five years and no residual value. The old machine could be sold now for $5,900. The annual cash operating costs for the old machine are $5,000, but for the new machine they would be only $2,500. Gross revenue from the products would be $12,000 annually for either machine. The company should a. keep the old machine to avoid a $5,900 loss on its disposal. b. keep the old machine to avoid an $8,500 decrease in cash. c. keep the old machine to avoid a $1,700 loss on its disposal. d. replace the old machine. ***PLEASE EXPLAIN****