You have just received notice that a customer of yours with an Account Receivable balance of $100 has gone bankrupt and will not make any future payments. Assuming you use the allowance method, the entry you make to write this account off is to

debit allowance for doubtful debt $100

credit accounts receivable       $100

Explanation:

When a company makes sales on account, debit accounts receivable and credit sales. Based on assessment, some or all of the receivables may be uncollectible.  

To account for this, debit bad debit expense and credit allowance for doubtful debt. Should the debt become uncollectible (i.e go bad), debit allowance for doubtful debt and credit accounts receivable.

Where a debit that had previously been determined to have gone bad gets settled, debit cash and credit bad debt expense.

the correct answer will be d