Which AWS database solution will meet these requirements?

Explanations:

While Amazon RDS for MySQL can be deployed in multiple regions and can utilize AWS DMS for replication, it may not efficiently handle the expected scale of thousands of transactions per second. Additionally, the multi-Region setup introduces complexity and potential latency, making it less suitable for the requirement of under 100 ms response times for active reads and writes.

Amazon Aurora MySQL with global database functionality supports cross-region replication and can handle increased traffic. However, it does not provide active writes in multiple regions, which is a requirement for the application. It allows for read replicas in different regions but not for simultaneous active writes, making it unsuitable for the stated needs.

Amazon DynamoDB with global tables is designed for high availability and scalability. It supports active reads and writes in multiple AWS regions simultaneously and is optimized for low-latency performance, making it capable of achieving response times of less than 100 ms. This option aligns well with the expected growth in traffic and the application requirements.

Amazon DocumentDB supports replication and can handle multiple regions, but it is not as optimized for high scalability as DynamoDB. It is primarily designed for document-oriented data rather than the relational structure of the described application. While it provides capabilities for global clusters, it may not meet the performance and scalability requirements as effectively as DynamoDB for this use case.