The correct answer is D, Amazon Elastic File System (Amazon EFS). Amazon EFS is a fully managed file storage service that provides shared file storage that can be accessed by multiple Amazon EC2 instances concurrently. It is designed to be highly available and scalable, allowing you to create and configure filesystems that can grow and shrink automatically as you add or remove files. Amazon EFS supports the Network File System version 4 (NFSv4) protocol and provides a simple way to share files between multiple instances without the need to set up and manage your own file servers.