Which of the following best describes the concept of the aging method of receivables?

a. An accurate estimate of bad debt expense may be arrived at by multiplying historical bad debt rates by the amount of credit sales made during a period.

b. The precise amount of bad debt expense may be arrived at by multiplying historical bad debt rates by the amount of credit sales made during a period.

c. Accounts receivable should be directly written off when the due date arrives and the customers have not paid the bill.

d. Estimating the appropriate balance for the allowance for doubtful accounts results in the appropriate value for net accounts receivable on the balance sheet.