A company is developing an ecommerce application that will consist of a load-balanced front end,...

https://docs.aws.amazon.com/AmazonECS/latest/developerguide/Welcome.html

1. Relational database: RDS

2. Container-based applications: ECS

"Amazon ECS enables you to launch and stop your container-based applications by using simple API calls. You can also retrieve the state of your cluster from a centralized service and have access to many familiar Amazon EC2 features."

3. Little manual intervention: Fargate

You can run your tasks and services on a serverless infrastructure that is managed by AWS Fargate. Alternatively, for more control over your infrastructure, you can run your tasks and services on a cluster of Amazon EC2 instances that you manage.