(P1)Mohr Company purchases a machine at the beginning of the year at a cost of $24,000. The machine is depreciated using the units-of-production method. The company estimates it will use the machine for 5 years, during which time it anticipates producing 40,000 units. The machine is estimated to have a $4,000 salvage value. The company produces 9,000 units in year 1 and 6,000 units in year 2. Depreciation expense in year 2 is:
选项：

A:$3,000.
B:$4,000.
C:$9,600.
D:$4,500.
E:$14,400.