Hayden Company is considering the acquisition of a machine that costs $576,000. 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. 6.3 years

b. 1.2 years

c. 8.6 years

d. 7.4 years