A bring-your-own-device environment increases exposure to malware because personal devices may not be configured, patched, monitored, or protected to the same standard as organization-owned devices. Employees may install unapproved applications, connect to insecure networks, delay updates, or mix personal and business use. Less efficiency and lower employee satisfaction are not typical BYOD benefits or core risks; BYOD often improves convenience and flexibility. Higher organizational device cost is also not the primary risk because the employee owns the device, although support and monitoring costs may increase. Internal auditors should review mobile device management, malware protection, encryption, acceptable use, patching, remote wipe, incident response, and user awareness. Therefore, Option D is correct.