A three-tier web application has web servers in a public subnet and application and database servers in private subnets. A third-party virtual firewall appliance from AWS Marketplace is deployed in an inspection VPC and has an IP interface that accepts packets. A solutions architect must ensure all incoming traffic is inspected by the appliance before reaching the web servers, with the least operational overhead. Which solution meets these requirements?

The correct solution is to deploy a Gateway Load Balancer (GWLB) in the inspection VPC and create a GWLB endpoint. GWLB is specifically designed for deploying, scaling, and managing virtual appliances such as firewalls. It transparently passes all traffic (including IP headers) to the appliance for inspection and then back to the destination, ensuring all incoming traffic is inspected. The GWLB endpoint acts as a transparent network gateway, receiving traffic and forwarding it to the GWLB. Creating a Network Load Balancer or Application Load Balancer in the application's public subnet would not effectively route all incoming traffic through the appliance for inspection in a transparent manner. These load balancers are designed to distribute traffic to application instances, not to act as transparent inspection points for network appliances. Deploying a transit gateway alone would require complex routing configurations and would not inherently provide the transparent traffic steering capabilities of a GWLB for appliance inspection.