The asset section of the January 1, 20X9, balance sheet of Big Valley Company includes a machine which was acquired on January 1, 20X5. The machine's original cost was $500,000, and the estimated life was determined to be 10 years. The estimated residual value was zero, and the straight-line method of depreciation was chosen. The book value of the machine as of January 1, 20X9, is: A. 9% B. 14.4% C. 18% D. 35%