Answer :
The answer would be : Both A and B above
When we change the estimation method of depreciation , we should change the depreciation calculation that we made in the past before we impose the new method, so we not underestimate or overestimate the Assets
When we change the estimation method of depreciation , we should change the depreciation calculation that we made in the past before we impose the new method, so we not underestimate or overestimate the Assets