B

Explanation: Due diligence work is a direct reporting engagement (B), as it involves the auditor reporting findings directly to the client or a third party, often in the context of mergers or acquisitions. It is not an attestation engagement (A), which provides assurance on a subject matter. Compilation engagements (C) involve preparing financial information without assurance. Agreed-upon procedures (D) involve specific procedures agreed with the client, not typical for due diligence.