A company runs applications on Amazon EC2 instances backed by Amazon Elastic Block Store (Amazon EBS) using the latest Amazon Linux. Employees store and retrieve files 25 GB or larger and the company experiences availability issues. The solution must not require transferring files between EC2 instances and files must be available across many EC2 instances and across multiple Availability Zones. Which solution meets these requirements?

Amazon EFS is the correct solution because it provides a scalable, shared file system that can be mounted across multiple EC2 instances in different Availability Zones simultaneously. This directly addresses the requirement for files to be available across many EC2 instances and multiple Availability Zones without transferring files. EFS is designed for shared access and high availability, making it suitable for the company's availability issues. Migrating to Amazon S3 would require employees to access files directly from S3, which might change application architecture and doesn't provide a traditional file system interface for EC2 instances. Taking an EBS snapshot and mounting it across EC2 instances is not feasible because an EBS volume can only be attached to a single EC2 instance at a time. Creating an AMI and using instance store volumes is incorrect because instance store volumes are ephemeral and data would be lost if the instance stops or terminates, and they are not designed for shared access across multiple instances.