(i) Mesh

In a mesh topology every device has a dedicated point-to-point link to every other device.

• Security: data travels along a private link, not a shared medium, so other nodes can't eavesdrop.
• Robustness: failure of one link doesn't isolate any node — alternate paths always exist.
• No traffic/collision problem: since links aren't shared, there's no contention or traffic congestion between unrelated device pairs.

Star, Ring, and Bus all rely on a shared medium or central point, so they don't offer all three properties simultaneously.