For a company using the straight-line method of depreciation that changes the estimated useful life from 20 years to 15 years remaining as at the beginning of the year, ti accountant should do the following: O a. Compute current year depreciation as (carrying amount - residual value) divided by 15 years. O b. Adjust prior year's depreciation. O c. Adjust the amount of accumulated depreciation as at the beginning of the year. O d. Compute current year depreciation as (cost-residual value) divided by 15 years