Some company purchased a vehicle for deliveries for $45,000 at the beginning of 2017. The vehicle had an estimated life of 6 years, and an estimated residual value of $3,000. Company used the straight-line depreciation method. At the beginning of 2021, company incurred $4,000 to replace the vehicle's transmission. This resulted in a 2-year extension of the vehicle's useful life and a revised residual value of $1,000. How much annual depreciation expense should the company record for the remaining four years of the vehicle's life?

A. $5,000

B. $7,000

C. $4,000

D. $4,500