The correct answer is 'Configure VRRP on the routers,' because VRRP is designed to prevent a single point of failure in the default gateway scenario by allowing multiple routers to work together to create a virtual router. The virtual router is presented as a single default gateway to the hosts on the subnet. If the primary (master) router becomes unavailable, one of the backup routers takes over the role almost instantly, providing high availability. 'Configuring RIP' is incorrect because RIP is a routing protocol used for determining the best path to a network destination, not for gateway redundancy. 'Setting static routes on each host' would not provide automatic failover in the event of a gateway failure. 'Enabling Spanning Tree Protocol' is also incorrect because STP is used to prevent network loops in a Layer 2 switch network and is not related to gateway redundancy.