A machine with a cost of $64,008 has an estimated residual value of $4,747 and an estimated life of 6 years or 18,419 hours. It is to be depreciated by the units-of-activity method. What is the amount of depreciation for the second full year, during which the machine was used 4,155 hours? Do not round your intermediate calculations. Oa. $14,439.07 Ob. $19,753.67 Oc. $13,368.23 Od. $9,876.83