Final answer:
Dynamic Routing is best suited for simple high-availability because it allows for automatic network adjustments in response to topology changes and traffic, unlike static, policy-based, or default routing.
Step-by-step explanation:
The best routing policy type for implementing simple high-availability is Dynamic Routing. Unlike static routing, dynamic routing protocols allow the network to automatically adjust to changing topologies and traffic conditions, making it possible to reroute traffic if a primary link goes down. Protocols like OSPF (Open Shortest Path First) and BGP (Border Gateway Protocol) can detect network failures and recalibrate routes quickly. In contrast, static routing would require manual reconfiguration in case of a route failure, which is not conducive to high-availability needs. Policy-based routing is more about traffic management based on policies, and default routing is typically used for directing traffic to an ultimate gateway when no other specific route is known, which is not directly related to high availability.