A Layer 3 capable switch is the correct choice because it can segment network traffic into different VLANs to reduce broadcast domains, and perform inter-VLAN routing without the need for an external router. This improves overall network performance and is suitable for a SCADA network where reliability and efficiency are critical. A hub cannot segment traffic and creates one large collision domain, leading to inefficiencies and potential network collisions. A wireless LAN controller is specifically designed to manage wireless access points, and is not applicable for segmenting wired SCADA network traffic. A repeater merely extends the signal but does not segment the traffic or reduce broadcast domains.