Which service provides adjustable storage for AWS users needing consistent performance?

The correct answer is Amazon EBS (Elastic Block Store) because it is designed specifically for workloads requiring consistent, low-latency performance and adjustable storage. Amazon EBS provides block storage that can be dynamically scaled up or down based on the needs of the application, ensuring that users can maintain stable performance even as their data storage requirements change. Additionally, Amazon EBS allows users to define the performance characteristics such as IOPS (Input/Output Operations Per Second) when creating volumes, giving them the flexibility needed for applications that depend on high performance.

Amazon S3 is designed for object storage and is primarily used for unstructured data; while it can offer good performance, it does not specifically provide the same level of consistent performance and storage adjustability as EBS. AWS Lambda is a serverless compute service that runs code without provisioning or managing servers, and is not utilized for storage solutions in the same context. Amazon Glacier is an archival storage service focused on long-term storage and is not built for consistent performance, as it is optimized for infrequent access and retrieval times can be longer compared to the other services.