Which of the following provides the MOST secure method for Network Access Control (NAC)?

MAC filtering is easily bypassed because MAC addresses are visible in unencrypted network traffic and can be spoofed by an attacker using readily available tools, providing only superficial security.

802.1X is a port-based NAC standard that requires devices to authenticate via an authentication server (typically RADIUS) using EAP before being granted network access. It validates identity through credentials, certificates, or tokens, making it extremely difficult to bypass compared to identifier-based methods. This ensures only authorized users and devices gain network access, making it the gold standard for NAC security.

Application layer filtering is a firewall/proxy technique used to inspect and control traffic content after network access is already granted, not a mechanism for controlling initial network admission.

Network Address Translation (NAT) is a technique for mapping private IP addresses to public ones to conserve address space and provide basic obscurity, but it does not authenticate or authorize devices seeking network access.