The Asset Section of the January 1, 20X7, Balance Sheet

The asset section of the January 1, 20X7, balance sheet of Petticoat Company includes a machine which was acquired on January 1, 20X3. 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. If operating income before depreciation is $90,000, the rate of return on average net book value for 20X7 is:

A) 32.79%
B) 14.55%
C) 13.33%
D) 16.00%