Hayden Company is considering the acquisition of a machine that costs $399,000. The machine is expected to have a useful life of 6 years, a negligible residual value, an annual net cash inflow of $86,000, and annual operating income of $73,100. The estimated cash payback period for the machine is (round to one decimal place) Oa. 6.6 years Ob. 5.5 years Oc. 1.2 years Od. 4.6 years