The best recommendation to reduce the risk associated with potential system compromise when a vendor stops releasing security patches and updates for a business-critical legacy system is to segment the system on its own network. Network segmentation is the process of dividing a network into smaller subnetworks or segments, based on different criteria, such as function, location, or security level. Network segmentation helps to isolate the system from the rest of the network, and limit the exposure and access to the system. Network segmentation also helps to improve the performance and security of the network, by reducing the network traffic and congestion, and enhancing the monitoring and control capabilities. The other options are not as effective as segmenting the system on its own network, although they may provide some additional protection or recovery options. Ensuring regular backups take place, virtualizing the system in the cloud, and installing antivirus software on the system are all measures that can helpto reduce the risk of data loss or system damage, but they do not address the root cause of the risk, which is the lack of security patches and updates for the system. References = Risk and Information Systems Control Study Manual, Chapter 3, Section 3.2.1, page 3-11.