During 2020, a company wrote off $6,000 in uncollectible accounts receivable. At the end of the year, they estimated bad debt expense using a percent of gross sales. In 2021, the company recovered a $1,000 account that was written off in 2020. The recording of this recovery would include a

a. debit to retained earnings

b. credit to accounts receivable

c. debit to allowance for doubtful accounts

d. credit to prior period adjustments