Which of the following would be BEST to use to protect a network?

Antivirus software protects individual endpoints from malicious software but does not provide comprehensive network-level traffic filtering or access control.

A proxy server acts as an intermediary for requests from clients seeking resources from other servers, offering some security benefits by masking client IP addresses, but its primary role is not general network protection.

Anti-malware software, similar to antivirus, focuses on detecting and removing malicious software on individual devices, not protecting the overall network perimeter.

A firewall is a network security device that monitors and filters incoming and outgoing network traffic based on a set of predetermined security rules. It acts as a barrier between a trusted internal network and untrusted external networks, providing the primary defense for network protection by preventing unauthorized access and malicious data flows.