The correct answer is a Host-based Intrusion Prevention System (HIPS). A HIPS not only detects intrusions like a HIDS but also has the capability to take immediate action to block potential threats. The real-time automatic response is a key differentiator of HIPS from HIDS, which typically only alerts on potential security issues. A firewall can block unwanted traffic based on a set of defined rules but doesn't provide the system event and log file analysis typically associated with a HIDS/HIPS. Anti-virus software primarily focuses on detecting and removing malware but doesn't offer the comprehensive event analysis and real-time automatic intrusion prevention of a HIPS.