A file-processing application requires a shared POSIX file system mounted concurrently by Linux instances in several AZs. Which service most directly fits?

1. Amazon EFS with the required mount targets, network permissions, and resilience configuration.
2. Instance store on one application server.
3. S3 mounted as a guarantee of identical POSIX filesystem semantics.
4. One ordinary EBS volume attached independently to all instances in all AZs.