please explain

21) Brandy Enterprises discarded a computer that was fully depreciated and had no residual value. As a result of this transaction, Brandy will A) report a loss equal to the historical cost of the computer. B) debit the Accumulated Depreciation - Computer account: debit Loss on Disposal of Computer account, and credit the Computer account. C) zero out the Computer and Accumulated Depreciation - Computer accounts. D) debit the Computer account and credit the Accumulated Depreciation - Computer account