A FedEx airplane costs $50 million and is expected to fly 500 million miles during its 10-year life. Residual value is expected to be zero because the plane was used when acquired. If the plane travels 20 million miles the first year, how much depreciation should FedEx record under the units-of-production method?

a. $2 million

b. $5 million

C. $10 million

d. Cannot be determined from the data given