Amazon ECS with Fargate and Auto Scaling enables automating the scaling of containers without the need to manage the underlying server infrastructure. When traffic to the web application increases, ECS Auto Scaling adds more containers to handle the load, and when traffic decreases, it removes unnecessary containers to reduce costs. Amazon ECS on EC2 would also allow for scaling, but would require additional management of EC2 instances. AWS Lambda is not suitable for container orchestration. Amazon EKS does provide orchestration for Kubernetes but wasn't specified as a requirement, making ECS with Fargate and Auto Scaling the best direct answer to requirements stated.