The correct answer is:

(D) Fire Proxy Service

Fire Proxy Service is not a known or standard firewall technique. The correct firewall techniques are:

• (A) Packet filters: These filter traffic based on predefined rules.
• (B) Application Gateways: These filter traffic based on application-level data.
• (C) Proxy Server: A proxy server acts as an intermediary between users and the services they wish to access, helping with security and anonymity.