The auditor is studying a ratio of accounts payable turnover in days. Which of the following indicates a potential risk of unrecorded liabilities?

a. Accounts payable turnover in days increased from 28 days to 45 days from year one to year two.

b. Accounts payable turnover in days increased from 28 days to 30 days from year one to year two.

c. Accounts payable turnover in days decreased from 28 days to 15 days from year one to year two.

d. Accounts payable turnover in days decreased from 30 days to 25 days from year one to year two.