Hayden Company is considering the acquisition of a machine that costs $578,000. The machine is expected to have a useful life of 6 years, a negligible residual value, an annual net cash flow of $100,000, and annual operating income of $85,000. What is the estimated cash payback period for the machine (round to one decimal points)? Oa. 1.2 years Ob. 8.0 years Oc. 5.8 years Od. 6.8 years