**A. NAC (Network Access Control)** would BEST meet the requirements described.
NAC is a technology that helps control and manage access to a network by enforcing security policies, ensuring compliance with security requirements, and verifying the health and configuration of devices before granting network access. In this scenario, a NAC solution could enforce access control and ensure that only authorized individuals and devices meeting patching, antivirus, and configuration requirements are allowed to connect to the environment. It provides a comprehensive approach to network security and access control.