Which of the following would be the GREATEST concern during a financial statement audit?

While a lack of backup for key approvers is an operational concern for business continuity, it doesn't directly or immediately compromise the accuracy of historical financial statements in the same way as unapproved reporting procedures.

Untested system capacity is an operational risk impacting system performance and availability, but it does not inherently mean that the financial data generated is inaccurate or that the controls over reporting are inadequate.

Unapproved procedures for generating key reports directly introduce a high risk to the accuracy, completeness, and reliability of financial statements, as the auditor cannot verify the controls or methodology used to produce critical financial information. This directly impacts the audit opinion.

The fact that a financial management system is cloud-based is not inherently a concern; rather, the controls implemented by the cloud provider and the organization over that system would be the focus of the audit.