Hayden Company is considering the acquisition of a machine that costs $558,000. The machine is expected to have a useful life of 6 years, a negligible residual value, an annual net cash flow of $90,000, and annual operating income of $76,500. What is the estimated cash payback period for the machine (round to one decimal points)? O a. 1.2 years b. 6.2 years O c. 8.5 years Od. 7.3 years