Caterpillars Inc., a manufacturing company, acquired equipment on January 1, 2012 for $500,000. Estimated useful life of the equipment was 7 years and the estimated residual value was $10,000. On January 1, 2015, after using the equipment for 3 years, the total estimated useful life has been revised to 9 years. Residual value remains unchanged. The company uses the straight-line method of depreciation. Calculate depreciation expense for the year 2015.

a. $48,333

b. $46,667

c. $26,666

d. $33,333