D is corrent. When an account is written off, the journal entry is debit the allowance for uncollectible accounts and credit accounts receivable. If the account is subsequently collected, an entry is made to reinstate the account receivable by debiting accounts receivable and crediting the allowance for uncollectible accounts. A second entry is made for the cash collection which involves debiting cash and crediting accounts receivable. Therefore, there is no change in accounts receivable when a previously written-off account is collected; accounts receivable is debited for the reinstatement, and credited for the payment. However, when the previously written-off account is collected, there is an increase in the allowance for uncollectible accounts.
A is incorrect because there is a net effect of zero on accounts receivable and an increase to the allowance, not a decrease.
B is incorrect because there is a net effect of zero on accounts receivable and in increase to the allowance.
C is incorrect because there is an increase to the allowance, not a decrease.
