Assume Nationwide Communications purchased a new piece of equipment on January 1, 2014 that cost $30,000. The estimated useful life is five years and estimated residual value is $8,000. If Nationwide uses the straight-line method for depreciation, what is the asset's book value at the end of 2015? O A $18,000 OB. $21,200 OC. $13,200 OD. $29,200