Deciding which PPE components to depreciate separately is called Select one: O a. group depreciation. O b. separate depreciation. O c. componentization. d. individual asset depreciation. Depreciation commences or continues when Select one: O a. The asset has been paid for. O b. The asset is available for use. O c. The asset is taken out of service. O d. The asset's fair value can be recovered. If a company uses the units of production method for calculating depreciation on its factory machinery, the credit to accumulated depreciation from period to period during the life of the firm will Select one: O a. vary with unit sales. b. vary with sales revenue. O c. vary with production. O d. be constant