(Ch10) A machine that has been used for 1 year has a salvage value of $10,000 now, which will drop by $2000 per year. The maintenance costs for the next 4 years are $1250,$1450,$1750, and $2250. Determine the marginal cost to extend service for Year 4 if the MARR is 8%. a) $3550 b) $4690 c) $3305 d) $4570