Which solution will meet these requirements with the LEAST operational overhead?

Explanations:

Amazon RDS for SQL Server is a fully managed service that simplifies database management tasks such as backups, patching, and scaling. Using read replicas allows for offloading reporting tasks from the primary database, reducing operational overhead while still utilizing the same SQL Server environment.

While Microsoft SQL Server on Amazon EC2 offers flexibility, it requires manual management of the server, including backups, updates, and scaling, leading to higher operational overhead compared to managed services like RDS. Always On availability groups can be complex to set up and manage.

Amazon DynamoDB is a NoSQL database, which is not compatible with SQL Server databases without significant changes to the application. Migrating to DynamoDB would require substantial re-engineering of the application and may not support the same transactional features as SQL Server, increasing operational complexity.

Amazon Aurora MySQL is a different database engine and requires a migration away from SQL Server, which could involve application changes. While it provides read replicas, the migration would not fulfill the requirement to maintain the SQL Server environment, leading to increased operational overhead due to the necessary modifications.