Hayden Company is considering the acquisition of a machine that costs $421,000. The machine is expected to have a useful life of 6 years, a negligible residual value, an annual net cash inflow of $91,000, and annual operating income of $77,350. The estimated cash payback period for the machine is (round to one decimal place)

a.6.6 years

b.5.4 years

c.4.6 years

d.1.2 years