When multiple routes have the same destination prefix, which attribute does the firewall use first...

Basic Concept: When destination prefix length is the same, route selection compares administrative distance to choose the preferred source protocol before metric.

Why A is Correct: Administrative distance is evaluated first among equal destination prefixes learned from different route sources.

Why B is Wrong: Route metric is a routing-related concept, but it is not the PAN-OS routing attribute, prerequisite, or route-selection behavior required by this question.

Why C is Wrong: Next-hop availability is a routing-related concept, but it is not the PAN-OS routing attribute, prerequisite, or route-selection behavior required by this question.

Why D is Wrong: Longest prefix match is a routing-related concept, but it is not the PAN-OS routing attribute, prerequisite, or route-selection behavior required by this question.