A company wants to ensure employees are allowed to copy files from a virtual desktop during the workday but are restricted during non-working hours. Which of the following security measures should the company set up?

Time-based access control (TBAC) is the most suitable security measure because it specifically restricts user access to resources based on the time of day or day of the week. This directly addresses the requirement to allow file copying during working hours and restrict it during non-working hours. Digital rights management (DRM) focuses on controlling the use, modification, and distribution of copyrighted material, not on time-based access to general files. Role-based access control (RBAC) assigns permissions based on a user's role within an organization, which doesn't directly manage access based on time. Network access control (NAC) authenticates and authorizes devices connecting to a network, ensuring they meet security policies, but it doesn't inherently manage file copy permissions based on time.