Which of the following is a unique feature of attribute-based access control (ABAC)?

Granting access based on group affinity describes Role-Based Access Control (RBAC), where permissions are assigned to roles or groups rather than evaluated attributes.

Biometric authentication is an authentication mechanism (something you are), not an access control model - it verifies identity but does not define how authorization decisions are made.

ABAC uniquely supports fine-grained, policy-driven access decisions based on multiple attributes - including environmental attributes like time of day. This means access can be permitted or denied depending on contextual conditions (e.g., only between 9 AM and 5 PM), which is a hallmark capability of ABAC that distinguishes it from role-based or discretionary models.

Username and password authentication is a basic credential-based identity verification method, not a feature of any specific access control model like ABAC.