Which of the following items would not be considered when analyzing accounts receivable and allowance for doubtful accounts?

a. The relationship among changes in sales, accounts receivable and the allowance for doubtful accounts.

b. A comparison of actual write-offs relative to amounts recognized as bad debts.

c. The relationship between accounts receivable, inventory , and accounts payable.

d. An analysis of the Valuation and Qualifying Accounts schedule required in the Form 10-K.