Allowance for Doubtful Accounts has a credit balance of $800 at the end of the year (before adjustment), and an analysis of accounts in the customer ledger indicates that the estimated amount of uncollectible accounts should be $16,000. Based on the estimate above, which of the following adjusting entries should be made?

a. debit Bad Debt Expense, $15,200; credit Allowance for Doubtful Accounts, $15,200

b. debit Allowance for Doubtful Accounts, $800; credit Bad Debt Expense, $800

c. debit Bad Debt Expense, $16,800; credit Allowance for Doubtful Accounts, $16,800

d. debit Bad Debt Expense, $800; credit Allowance for Doubtful Accounts, $800