An e-commerce company has hired an AWS Certified Solutions Architect Professional to transform a standard three-tier web application architecture in AWS. Currently, the web and application tiers run on EC2 instances and the database tier runs on RDS MySQL. The company wants to redesign the web and application tiers to use API Gateway with Lambda Functions with the final goal of deploying the new application within 6 months. As an immediate short-term task, the Engineering Manager has mandated the Solutions Architect to reduce costs for the existing stack. Which of the following options should the Solutions Architect recommend as the MOST cost-effective and reliable solution?