What is the highest-metric route to subnet 2 visible in the output of the show ip route eigrp command given R1’s route metrics?

The highest-metric route to a subnet refers to the route with the greatest EIGRP metric value that is still considered viable for routing. In EIGRP, routes are categorized into successor and feasible successor routes. The successor route is the primary route to the destination and has the lowest metric, while the feasible successor routes are backup routes that can be used if the successor route becomes unavailable.

In this context, the feasible successor route with a metric of 350 is the choice that reflects the highest metric among the valid routes to subnet 2. While the successor route has a metric of 100, making it the primary route, the feasible successor, although still significantly lower than the highest possible metric, qualifies as the highest among alternatives when you disregard active pathways.

The other choices suggest metrics that do not fall in line with EIGRP's criteria for what defines the highest-metric viable route. Thus, the feasible successor route holds significance as it is available for use within the EIGRP topology, showing that, even though it's not the primary path, it is still a reliable option when needed.