You plan an Azure deployment that includes three virtual networks in East US. Vnet1 will connect to your on-premises network by a Site-to-Site VPN. To ensure VMs in all three virtual networks can reach the on-premises network while minimizing cost, what should you recommend for Vnet2 and Vnet3?

Peering is the most cost-effective and efficient solution. It allows Vnet2 and Vnet3 to communicate with Vnet1 directly, and Vnet1 can then route traffic to the on-premises network via its Site-to-Site VPN gateway. This avoids the need for additional VPN gateways in Vnet2 and Vnet3, which would incur higher costs and management overhead. VNet-to-VNet VPN connections would require separate VPN gateways for each connection, increasing cost and complexity. Service endpoints are for securing access to Azure services, not for connecting virtual networks to on-premises networks. Route tables are used to control network traffic flow within and between subnets, but they don't establish the underlying connectivity between virtual networks or to on-premises networks.