WPA2/WPA3 mixed mode provides compatibility for older devices (that only support WPA2) while allowing newer devices to take advantage of stronger WPA3 encryption. This ensures maximum compatibility and security in a mixed-device environment. A). WPA3 only is most secure but not compatible with legacy devices. B). WPA2 only is secure but does not future-proof against WPA3-capable devices. D). WPA/WPA2 mixed mode is weaker due to WPA (deprecated, insecure). References (CompTIA Network+ N10-009): Domain: Network Security - Wi-Fi encryption standards, WPA2 vs WPA3, mixed-mode compatibility.