A company has deployed a multi-tier web application to support a website. The architecture includes an Application Load Balancer (ALB) in public subnets, two Amazon Elastic Container Service (Amazon ECS) tasks in the public subnets, and a PostgreSQL cluster that runs on Amazon EC2 instances in private subnets. The EC2 instances that host the PostgreSQL database run shell scripts that need to access an external API to retrieve product information. A solutions architect must design a solution to allow the EC2 instances to securely communicate with the external API without increasing operational overhead. Which solution will meet these requirements?