A company's web application has reliability issues. The application serves customers globally. The application runs on a single Amazon EC2 instance and performs read-intensive operations on an…

An Amazon CloudFront distribution primarily serves to cache static content and improve content delivery latency globally, but it does not address the underlying reliability issues of a single backend EC2 instance or the database's performance under load.

Running the application on EC2 instances within an Auto Scaling group behind an Application Load Balancer addresses the single point of failure and provides automatic scaling and healing for the application tier. Configuring Amazon RDS for MySQL with a Multi-AZ deployment ensures database availability and automatic failover, while an RDS Read Replica offloads read-intensive operations, significantly improving database performance and overall reliability with minimal application code changes.

AWS Global Accelerator improves performance by routing traffic to optimal endpoints, but it does not inherently make a single application instance or a database scalable or resilient against internal failures.

Migrating the application to AWS Lambda functions would improve scalability and reliability but typically requires significant re-architecting and development effort, which contradicts the 'LEAST development effort' requirement.