Your organization uses an SD-WAN across 40 branch offices that runs BGP. In Azure you have 20 virtual networks in a hub-and-spoke layout; the hub virtual network Vnet1 connects to the SD-WAN through a network virtual appliance (NVA) deployed in Vnet1. To allow BGP route advertisements to propagate between the Azure virtual networks and the SD-WAN with minimal administrative overhead, which solution should you implement?

Azure Route Server is the correct choice because it enables dynamic routing (BGP) between your NVA and the Azure Software Defined Network (SDN) without manually configuring user-defined routes (UDRs). It learns routes from your NVA and propagates them to all virtual networks peered with the hub, and vice-versa, ensuring full connectivity between your SD-WAN and Azure spokes with minimal administrative overhead. An Azure VPN Gateway is used for site-to-site or point-to-site VPN connections, not for integrating an NVA's BGP routes into the Azure SDN. A NAT gateway provides outbound internet connectivity and network address translation, unrelated to BGP routing. Azure Traffic Manager is a DNS-based traffic load balancer, not a routing solution for internal networks.