Castle Rock Owns a Machine That It Purchased on Jan

Castle Rock owns a machine that it purchased on Jan 1, 2019 for $400,000. The machine had an estimated useful life of 10 years with a production capacity for 80,000 units and was expected to have no residual value. The company uses the units-of-production method to record depreciation. The machine produced 15,000 units in 2019, 18,000 units in 2020 and 25,000 units in 2021. The machine was sold on December 31, 2021 for $350,000. What was the depreciation expense for 2021?

A) $39,000
B) $40,000
C) $90,000
D) $125,000