On January 1, 2021, Barney Rubble purchased the right to extract and sell gravel from an old rock quarry. The cost of the quarry rights was $280,000, with estimated salable rock of 35,000 tons. During 2021, Barney extracted 6,000 tons of rock. If Barney uses the units-of-production method, how much depletion expense should Barney record in 2021? $0 $48,000 $28,000 $280,000