A web server is overwhelmed by many slow, incomplete HTTP connections.

This scenario describes a Slowloris attack, a classic application-layer DoS attack covered in CEH v13 Network and Perimeter Hacking. Slowloris works by opening many HTTP connections and sending data very slowly, preventing the server from closing the connections.

Because the connections appear legitimate, the server keeps them open, eventually exhausting its connection pool. This causes legitimate users to experience timeouts and service unavailability—exactly as described.

ICMP and UDP floods consume bandwidth, which was ruled out. Fragmentation attacks target packet handling, not application-layer sessions.

CEH v13 highlights Slowloris as particularly dangerous because it requires minimal bandwidth and bypasses many traditional DoS defenses. Therefore, Option A is correct.