Explanation:

- Business Documents: These include invoices, receipts, and contracts. They are issued in the course of regular business and are critical for verifying the legitimacy of transactions.

- Statutory Documents: These are legally required documents, such as incorporation papers or compliance forms. While important, they do not specifically evidence day-to-day transactions.

- Auditors: They review and verify the accuracy of financial statements, but are not documents themselves.

- None: This option suggests no documents are needed, which wouldn’t adhere to accounting principles.

The correct answer is highlighted: Business Documents.