At the Beginning of 2017,Smoothie Town,Inc

At the beginning of 2017,Smoothie Town,Inc.has the following account balances:
Accounts receivable $40,000 (Debit)
Allowance for Bad Debts $6,000 (Credit)
During the year,credit sales were $820,000.Cash collected on credit sales was $750,000,and $15,000 was written off.Smoothie Town uses the aging-of-receivables method to record bad debts expense.The amount estimated as uncollectible was $28,000.The amount of Bad Debts Expense for 2017 is ________.

A) $37,000
B) $28,000
C) $9,000
D) $13,000