5-83. A 2,000 square foot house in New Jersey costs $1,725 each winter to heat with its existing oil-burning furnace. For an investment of $5,000, a natural gas furnace can be installed, and the winter heating bill is estimated to be $1,000. If the homeowner’s MARR is 6% per year, what is the discounted payback period of this proposed investment? (5.8)

(a) 7 years

(b) 8 years

(c) 9 years

(d) 10 years