Firewalls are the software or hardware systems that are able to control and monitor the traffic coming in and out the target network based on pre-defined set of rules. Which of the following types of

A data-driven firewall is not a recognized standard firewall category and has no defined mechanism for parsing SQL syntax within web requests.

A stateful firewall tracks TCP/UDP connection state but only inspects packet headers, not application-layer payload content, so it cannot detect SQL injection strings embedded in HTTP requests.

A packet (stateless) firewall filters based on IP addresses and ports alone and has no capability to inspect or parse application-layer data such as SQL statements within request bodies.

A WAF analyzes traffic at OSI Layer 7 (application layer), parsing HTTP request parameters, headers, and body content against rule sets designed to identify malicious patterns such as SQL injection strings. Because it understands application-layer semantics, it can block or sanitize injection attempts that lower-layer firewalls cannot see.