A machine with a cost of $480,000 has an estimated salvage value of $30,000 and an estimated useful life of 5 years or 15,000 hours. It is to be depreciated using the units-of-activity method of depreciation. What is the amount of depreciation for the second full year, during which the machine was used 5,000 hours? Select one: a. $130,000 b. $90,000 O c. $150,000 d. $160,000