Which AWS service meets these requirements?

Explanations:

AWS Lambda is a serverless compute service that runs code in response to events and automatically manages the compute resources. It is not designed for managing container orchestration, cluster size, or scheduling of Docker environments.

Amazon RDS (Relational Database Service) is a managed relational database service and does not provide features for managing container clusters or scheduling. It is focused on database management rather than container orchestration.

AWS Fargate is a serverless compute engine for containers that allows users to run and manage containerized applications without the need to provision or manage servers. It handles cluster size, scheduling, and environment maintenance, making it a suitable alternative for managing Docker environments.

Amazon Athena is an interactive query service that makes it easy to analyze data in Amazon S3 using standard SQL. It is not related to managing Docker environments, clusters, or container orchestration.