In 2017, Patterson Wholesale Company had net credit sales of $750,000. On January 1, 2017, Allowance for Doubtful Accounts had a credit balance of $18,000. During 2017, $30,000 of uncollectible accounts receivable were written off. Past experience indicates that the allowance should be 10% of the balance in receivables (percentage-of-receivables basis). If the accounts receivable balance at December 31 was $200,000, what is the required adjustment to Allowance for Doubtful Accounts at December 31, 2017? A. $20,000. B. $75,000. C. $32,000. D. $30,000.