Answer (C) is correct.
The entry to record bad debt expense under the allowance method is to
debit bad debt expense and credit the allowance account. When a specific
account is then written off, the allowance is debited and accounts
receivable credited. Net income is affected when bad debt expense is
recognized, not at the time of the write-off. Because accounts receivable
and the allowance account are decreased by the same amount, a write-off
of an account also has no effect on the net amount of accounts