The show bgp neighbors NEIGHBOR-IP advertised-routes command displays the prefixes that the Secure Firewall Threat Defense device is advertising to a specific BGP neighbor. It must be executed against the managed threat defense device through the Advanced Troubleshooting interface. The ordinary show route command displays routes installed in the local routing table, not the specific prefixes advertised to a neighbor.
Route injection is a configuration capability and does not provide the required verification output. Cisco's command reference confirms that the advertised-routes keyword displays all routes advertised to the specified BGP peer, including the network, next hop, metric, weight, and AS path. Therefore, option A directly verifies the routes being shared with the upstream router. Cisco Secure Firewall Threat Defense Command Reference