AT Company purchased a tractor at a cost of $60,000. The tractor has an estimated residual value of $10,000 and an estimated life of 8 years, or 12,000 hours of operation. The tractor was purchased on January 1, 2010 and was used 2,400 hours in 2010 and 2,100 hours in 2011. What method of depreciation will produce the maximum depreciation expense in 2011?

A. Straight-line

B. Double-declining-balance

C. All methods produce the same expense in 2010

D. Units-of-production