Which architecture offers the HIGHEST availability?

Explanations:

While adding a second ActiveMQ server and an additional consumer instance in another Availability Zone improves availability, it still relies on self-managed EC2 instances for both the message broker and the database. This introduces higher operational complexity and does not utilize AWS managed services, which can enhance reliability and availability. Additionally, replicating the MySQL database without using a managed service like RDS may complicate failover processes.

Using Amazon MQ provides a managed message broker, which improves availability, but it still relies on EC2 instances for the consumer application and MySQL database. While it does introduce some improvements, the architecture does not fully leverage AWS services that can enhance overall resilience and reduce operational overhead, particularly for the database component.

This option improves availability by using Amazon MQ and Multi-AZ for RDS, but it still requires managing the EC2 consumer instances, which can introduce operational complexity. The lack of an Auto Scaling group for the consumer instances means that the system may not effectively handle load changes or instance failures.

This architecture uses Amazon MQ with active/standby brokers for high availability of message processing, Auto Scaling for consumer instances to adapt to load changes, and Amazon RDS with Multi-AZ for the MySQL database. This option provides the highest level of availability while reducing operational complexity through the use of managed services and automatic scaling capabilities.