Amazon Elastic File System (EFS) is optimized for use cases where a shared file system is required. It supports NFS protocol, and multiple compute instances can simultaneously access the same file system, making it the correct choice for the described scenario. Alternative solutions like Amazon S3 and Amazon EBS do not offer file-level storage with concurrent access. S3 offers object storage with eventual consistency, which is not suitable for file systems requiring consistent and concurrent access, while EBS is a block-level storage that's only attachable to one instance at a time, ruling out simultaneous access.