Hayden Company is considering the acquisition of a machine that costs $$675,000.$ The machine is expected to have a useful life of $6$ years, a negligible residual value, an annual net cash inflow of $$150,000,$ and annual operating income of $$87,500.$ The estimated cash payback period for the machine is

a$.4\mathrm{.}5$ years

b$.3\mathrm{.}5$ years

c$.5$ years

d$.4$ years