Which of the following are valid modes of operation? (Choose all that apply)

Multilevel mode (or multi-level security, MLS) allows users with different security clearances to simultaneously process and access information at various classification levels within the same system. This mode requires robust security policies and mechanisms to ensure proper separation and access control based on user clearance and data classification.

'Restricted mode' is not a standard, formal security mode of operation like MLS or Dedicated.

Dedicated mode implies that a system is designed to operate for a single classification level and all users must have clearance and a need-to-know for all information on the system. This provides a highly secure, but less flexible, operational environment where all resources are treated uniformly at the same security level.

'Allowed mode' is not a recognized mode of operation in computer security contexts.

'Access Mode' is a generic term referring to how access is granted, not a specific operational mode.