Oakland Tax Planning Service bought computer equipment for $21,000 on January 1, 2018. It has an estimated useful life of four years and zero residual value. Oakland uses the straight line method to calculate depreciation and records depreciation expense in the books at the end of each month. Calculate the amount of Depreciation Expense for the period, January 1, 2018 through September 30, 2018, for this equipment. (Round any intermediate calculations to two decimal places, and your final answer to the nearest dollar.) A. $5,688 O B. $5,250 C. $4,375 OD. $3,938