A machine was depreciated for 30 of 50 years when it was discovered that the estimated life of 50 years was used erroneously. That 50-year life was for buildings: the estimated life of all machines was 40 years. The item qualifies as a prior period adjustment. Indicate the appropriate accounting: Select one: a. Continue to depreciate the machine over the original 50-year life b. Depreciate the remaining book value over the remaining life of the asset c. Adjust accumulated depreciation to its appropriate balance through net income, based on a 40-year life and then depreciate the adjusted book value as though the estimated life has always been 40 years O d. Adjust accumulated depreciation to its appropriate balance through retained earnings, based on a 40-year life, and then depreciate the adjusted book value as though the estimated life has always been 40 years