Correct Answer: Implement an AWS Lambda function that is invoked by an RDS event. The function pushes the update event to an Amazon SNS topic, which fans out the data to multiple Amazon SQS queues for downstream systems to consume.

Explanation: The most scalable and loosely coupled design involves:

Using an RDS event or custom change tracking mechanism to trigger a Lambda function.
The Lambda publishes the message to an Amazon SNS topic, which acts as a fan-out mechanism.
Each Amazon SQS queue subscribed to the SNS topic delivers the message to one or more downstream systems.

This pattern ensures durable delivery, decouples processing, and supports multiple subscribers. It avoids tight coupling and increases flexibility.

Why the other options are incorrect:

Publishing directly to Lambda from SNS limits message durability and visibility control.
Using only a standard SQS queue lacks fan-out capability.
FIFO queues offer ordering but reduce fan-out scalability and are unnecessary here.

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