Which AWS service is primarily used for object storage?

Amazon S3, or Simple Storage Service, is specifically designed for object storage, making it the correct answer. It allows users to store and retrieve any amount of data at any time from anywhere on the web. S3 is highly scalable, durable, and secure, enabling users to manage their data with ease and efficiency.

In S3, data is stored as objects within buckets, which serve as containers. Each object consists of the data itself, metadata, and a unique identifier. This architecture makes it particularly suited for applications that require the storage of unstructured data like images, videos, backups, and large data sets.

The other services listed serve different purposes: Amazon EC2 provides virtual computing environments (instances) for running applications, making it ideal for scalable cloud computing needs. Amazon RDS (Relational Database Service) is used for managing relational databases while providing automated backups, patching, and scaling. Amazon Lambda is focused on serverless computing, allowing users to run code in response to events without managing servers.

Therefore, when looking for an AWS service primarily focused on object storage, Amazon S3 is the clear choice.