On January 1, 2010, Knapp Corporation acquired machinery at a cost of $500,000. Knapp adopted the double-declining balance method of depreciation for this machinery and had been recording depreciatin over an estimated useful life of ten years, with no residual value. At the beginning of 2013, a decision was made to change to the straight-line method of depreciation for the machinery. The depreciation expense for 2013 woul be...

a. $25,600

b. $36,572

c. $50,000

d. $71,428