A company is planning to migrate its on-premises transaction-processing application to AWS. The application runs inside Docker containers that are…

This solution meets all the specified requirements. AWS Fargate for Amazon ECS is a serverless compute engine for containers that eliminates the need to provision and manage servers, satisfying the requirement to stop administering the Docker hosting environment. Amazon Elastic File System (Amazon EFS) provides a simple, scalable, and fully managed elastic file system. It can be mounted by multiple Fargate tasks simultaneously, providing the required shared storage. EFS is designed for low-latency access and offers Elastic Throughput mode, which automatically scales throughput performance up or down based on the application's workload, perfectly addressing the need for unpredictable transaction volumes.

A. Amazon S3 is an object store, not a file system. It is not suitable for the low-latency, file-based I/O required by a transactional application and would likely necessitate application code changes.
C. An Amazon EBS volume can only be attached to a single task at a time. It does not provide the shared storage needed for multiple containers to access the same transaction data concurrently.
D. This option requires the company to install and manage Docker on Amazon EC2 instances, which directly contradicts the requirement to stop administering the Docker hosting environment. ---
References:
1. AWS Fargate Documentation: "AWS Fargate is a serverless, pay-as-you-go compute engine that lets you focus on building applications without managing servers... AWS Fargate is compatible with both Amazon Elastic Container Service (ECS) and Amazon Elastic Kubernetes Service (EKS)." Source: AWS Fargate User Guide, "What is AWS Fargate?".
2. Amazon EFS for Amazon ECS: "With Amazon EFS, storage capacity is elastic, growing and shrinking automatically as you add and remove files. Your applications can have the storage they need, when they need it... You can use Amazon EFS file systems with your Amazon ECS tasks on AWS Fargate." Source: Amazon Elastic File System User Guide, "Using Amazon EFS file systems with Amazon ECS".
3. EFS Throughput Modes: "Elastic Throughput is the best throughput mode for spiky and unpredictable workloads with performance requirements that are difficult to forecast. With Elastic Throughput, you are not provisioning throughput in advance. Throughput is automatically scaled up and down for you by EFS." Source: Amazon Elastic File System User Guide, "Throughput modes".
4. Storage Options for ECS: "Amazon EBS volumes can be used for tasks hosted on Amazon EC2 instances. A unique EBS volume can be attached to a single task for persistent, block-level storage." This highlights the one-to-one mapping of EBS to a task, making it unsuitable for shared storage across multiple tasks. Source: Amazon Elastic Container Service Developer Guide, "Amazon ECS storage".