Refer to the exhibit. How would you redesign the network to improve availability of the routers 1A and 1B at the core site?

Graceful Restart Helper for OSPF only allows OSPF neighbors to maintain forwarding during an OSPF process restart and does not address physical router redundancy or availability.

Link bundles over multiple slots improve link-level bandwidth and redundancy but do not address the availability of the routers themselves as logical or physical devices.

APS (Automatic Protection Switching) Ethernet circuits provide circuit-level protection for specific links but do not improve overall router-level availability at the core site.

Creating a multichassis system - such as Cisco VSS (Virtual Switching System) or MC-LAG - combines two physical routers or switches into a single logical device, eliminating single points of failure at the router level. This provides active-active redundancy so that if one chassis fails, the other continues forwarding traffic without reconvergence delays. The result is significantly higher availability compared to operating two independent devices.