Hayden Company is considering the acquisition of a machine that costs $497,000. The machine is expected to have a useful life of 6 years, a negligible residual value, an annual net cash inflow of $88,000, and annual operating income of $74,800. The estimated cash payback period for the machine is (round to one decimal place) Oa. 7.8 years Ob. 6.6 years Oc. 1.2 years Od. 5.6 years