The correct answer is D, AWS Fargate. AWS Fargate is a serverless compute engine for containers that allows developers to run their containerized applications without managing the underlying infrastructure. It automatically provisions and manages the backend instances, such as the compute resources, storage, and networking required to run the containers. This ensures that developers only need to specify the necessary resources for their application, and Fargate will handle the rest, making it an ideal choice for deploying container-based applications with the specified requirements. Options A (Amazon EC2), B (Amazon Lightsail), and C (Amazon Elastic Kubernetes Service) do not provide the automatic provisioning and management of backend instances as Fargate does.