10. A factory machine was purchased for $60,000 on January 1, 2020. It was estimated that it would have a $12,000 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. If the actual number of machine hours ran in 2020 was 4,000 hours and the company uses the units-of-activity method of depreciation, the amount of depreciation expense for 2020 would be;

a. $6,000.

b. $9,600.

c. $12,000.

d. $4,800.