Final answer:
The implicit deny principle states that any action not explicitly allowed is automatically denied. This is a key concept in security to ensure unauthorized actions are not permitted by default.
Step-by-step explanation:
The implicit deny principle is a concept used often in computer security and access control systems. It is the foundation for secure access rules where access permissions are not granted until they are explicitly defined. This means that if a system does not expressly allow a particular action, it is automatically denied without requiring specific rules to block it. The correct answer to which statement best describes the implicit deny principle is B. All actions that are not expressly allowed are denied.