The Estimated Life of a Building That Has Been Depreciated

The estimated life of a building that has been depreciated 30 years of an originally estimated life of 50 years has been revised to a remaining life of 10 years.Based on this information, the accountant should

A) continue to depreciate the building 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 had always been 40 years.
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 had always been 40 years.