Adaptive identity is part of the Zero Trust control plane that involves dynamically assigning and adjusting permissions based on various factors such as user behavior, device, and location to ensure that trust is never assumed and is always being assessed. This reduces the threat scope by limiting access to resources to the minimum needed for the task at hand. In contrast, a policy administrator is an entity that oversees the policy creation, management and enforcement within an organization but does not continuously adjust permissions. 'Implicit trust zones' is an incorrect term as Zero Trust models do not rely on implicit trust but rather explicit continuous verification. 'Policy-driven access control' is a concept that represents a broader category which includes adaptive identity but not specifically about continuous evaluation of trust.