Final answer:
The mandatory access control model employs an explicit-deny philosophy, which means access is not granted unless explicitly allowed by policy. It is rule-based and considered prohibitive due to its inflexibility.
Step-by-step explanation:
The characteristic of the mandatory access control model that best fits the description is A. Employs explicit-deny philosophy. Mandatory access control (MAC) is a strict model that classifies all access permissions based on levels of security. It enforces an explicit-deny philosophy, meaning if a user or process is not granted explicit access rights by the policy, they will not have access. This model is not permissive; instead, it is considered prohibitive because it does not allow any flexibility in access beyond the strict policy rules. It is also rule-based in that the system strictly follows predefined security policies to control access.