As higher levels of assurance are desired from analytical procedures, more predictable relationships are required to develop the auditor’s expectation. Relationships involving income statement accounts tend to be more predictable than relationships involving only balance sheet accounts, and relationships involving transactions not subject to management discretion are generally more predictable. Answer (b) is correct because interest expense relates to the income statement, and because interest expense is subject to only limited management discretion, given the existence of the related debt.