A company hosts a multi-tier web application on Amazon Linux Amazon EC2 instances behind an Application Load Balancer. Instances run in an Auto Scaling group across multiple Availability Zones. The Auto Scaling group launches more On-Demand Instances when users request high volumes of static web content. The company wants to optimize cost. How should a solutions architect redesign the application MOST cost-effectively?

The most cost-effective solution is to use Amazon CloudFront with an Amazon S3 bucket for static content. CloudFront, a Content Delivery Network (CDN), caches static content closer to users, reducing latency and offloading requests from EC2 instances. S3 is a highly cost-effective and scalable storage solution for static files. This minimizes the need for EC2 instances to serve static content, allowing the Auto Scaling group to scale primarily for dynamic content, thus lowering overall compute costs. Using Reserved Instances (RIs) would reduce the cost of the existing EC2 instances, but wouldn't address the underlying issue of scaling for static content. Spot Instances are good for fault-tolerant workloads but are not ideal for serving static web content directly due to potential interruptions. AWS Lambda and API Gateway are suitable for dynamic APIs or serverless functions, not for directly hosting static website content in a cost-optimized manner compared to S3 and CloudFront.