A factory machine was purchased for $375,000 on January 1, 2017. It was estimated that it would have a $75,000 salvage value at the end of its 5-year useful life. It was also estimated that the machine would be run 40,000 hours in the 5 years. The company ran the machine for 4,000 actual hours in 2017. If the company uses the units-of-activity method of depreciation, the amount of depreciation expense for 2017 would be Select one: a. $75,000 b. $37,500. c. $60,000. d. $30,000