The correct service is Amazon Elastic File System (EFS). It provides a scalable file storage system that can be simultaneously accessed by multiple compute instances, making it suitable for workloads that require a centralized file repository accessible from various instances. In contrast, Amazon S3 is suitable for object storage and not as a shared file system. Amazon EBS is meant to provide persistent block storage for individual compute instances and does not natively support concurrent access. AWS Storage Gateway is mainly used to connect on-premises applications with cloud storage, which doesn't align with the requirement for shared data access by compute instances.