(Ignore income taxes in this problem.) A company with $600,000 in operating assets is considering the purchase of a machine that costs $72,000 and which is expected to reduce operating costs by $18,000 each year. These reductions in cost occur evenly throughout the year. How long is the payback period for this machine closest to, in years?

A. 4 years

B. 0.25 years

C. 33.3 years

D. 8.3 years