What kind of access control is based on user identity and granted by an administrator?

The type of access control that is based on user identity and granted by an administrator is indeed Discretionary Access Control (DAC). In a DAC model, the owner of a resource has the authority to make decisions regarding who can access that resource. This means that the administrator, acting on behalf of the resource owner, can assign or revoke access rights to individual users based on specific criteria, often reflecting the user's identity or other attributes.

DAC is characterized by its flexibility, as users may also have the authority to delegate their access rights to others. However, this also means that it relies heavily on the discretion of users and administrators, which can sometimes lead to security challenges if not properly managed.

In contrast, other models like Mandatory Access Control (MAC) enforce access policies defined by a central authority and do not grant users the discretion to modify these permissions. Role-Based Access Control (RBAC) assigns access based on user roles rather than individual identity alone. Automated Access Control does not specify how access is granted and could imply various forms of access control, including those that might not require explicit administrative input.

Thus, Discretionary Access Control is correctly identified as the method that aligns with access granted through user identity at the discretion of an administrator.