Jackson Companys Allowance for Doubtful Accounts has a debit balance of $500 at the end of the year (before adjustment). Jackson estimates uncollectible accounts expense at 3% of net sales. If net sales are $600,000, what is the amount of the adjusting entry to record bad debt expense for the year? a. $18,500 b. $17,500 c. $18,000 d. none of the above