A distribute list is the correct method to filter routes exchanged between EIGRP neighbors within the same autonomous system. In Cisco EIGRP designs, distribute lists can be applied inbound or outbound under the EIGRP process to control which routes are accepted from or advertised to neighbors. The filter can reference an access list, prefix list, or route map depending on platform and configuration style. This allows the designer to limit route visibility without changing the forwarding behavior of packets that are already routed.
Policy-based routing is a data-plane forwarding feature that changes next-hop selection for matching traffic; it does not filter EIGRP route advertisements between neighbors. Leak maps are used with route summarization to selectively advertise more specific routes through a summary, not as the general route-filtering method between EIGRP neighbors. Route tagging is valuable in redistribution designs to identify route origin and prevent feedback loops, but the tag alone does not filter routes unless a route map or distribute list uses it.
Therefore, the correct route-filtering mechanism between EIGRP neighbors is a distribute list.