Which service should a solutions architect use to meet these requirements?

Explanations:

Amazon Aurora is a MySQL-compatible relational database service that offers high performance and scalability. It is designed to handle a large number of concurrent queries and transactions, and it supports migration with minimal code changes. Additionally, it provides built-in optimizations for performance and availability.

Amazon DynamoDB is a NoSQL database service. Migrating from MySQL to DynamoDB would require significant code changes due to differences in data modeling and query capabilities. It may not be suitable for applications heavily reliant on SQL features.

Amazon ElastiCache is a caching service, not a database. While it can improve performance by caching frequently accessed data, it does not serve as a replacement for a MySQL database and does not support the required SQL features or concurrent transactions.

MySQL on Amazon EC2 would require managing the underlying infrastructure, including patching and tuning. This does not align with the goal of reducing operational overhead and optimizing performance through a managed service.