An air-gapped network is the best solution for ensuring high security and operational isolation as it is a physical isolation technique that completely separates the critical systems from unsecured networks, preventing any form of external access or data breach. Logical segmentation, while useful, doesn't offer physical isolation and can be bypassed if the network is compromised. A Virtual Private Network (VPN) provides secure remote access but does not address the requirement for physical isolation of the system. Using an Intrusion Prevention System (IPS) will add a layer of security but does not create isolated operational systems.