Explanation
The best way to connect all the VPCs for the company that is planning its cloud architecture and wants to use a VPC for each of its three products per environment in two regions, totaling 18 VPCs, is to use a hub and spoke model. A hub and spoke model is a networking model that uses a central hub VPC that connects to multiple spoke VPCs that host the products or workloads. The hub VPC can provide common services and security policies for the spoke VPCs, such as network virtual appliances, DNS servers, firewalls, or VPN gateways. The spoke VPCs can communicate with each other through the hub VPC, using private IP addresses or peering connections. A hub and spoke model can simplify the management and scalability of the network, as well as reduce the costs and complexity of peering multiple VPCs directly. Reference: Hub-and-spoke network topology - Cloud Adoption Framework