JC Inc. must install a new air-conditioning unit in its main plant. It is evaluating two different models: A and B; both are expected to last six years and are equally efficient. The cash flows (in millions) are listed below. JC's WACC is 7.5%. What unit would you recommend? If WACC changes to 9.5%, which unit would you recommend? t = 0 1 2 3 4 5 6 A -525 -25 -25 -50 -50 -75 -75 B - 175 -75 -125 - 125 - 150 -150 - 150 Indifferent B:B AA A:B ;A