Explanation

DynamoDB (A) and Simple Storage Service (C) are managed services where AWS handles the underlying infrastructure:

• DynamoDB: A fully managed NoSQL database service - AWS manages servers, patching, scaling, and replication
• Simple Storage Service (S3): A fully managed object storage service - AWS handles storage infrastructure, durability, and availability

EC2 (B) is NOT correct because it's Infrastructure as a Service (IaaS) where you manage the operating system, applications, and some network configurations

AWS Autoscaling (D) is NOT correct because while it automates scaling, it still requires you to manage the underlying EC2 instances and their configurations

These services represent the "managed services" model where AWS handles the undifferentiated heavy lifting of infrastructure management, allowing you to focus on your applications and business logic.