Which AWS service uses a combination of publishers and subscribers?

Explanations:

AWS Lambda is a compute service that runs code in response to events but does not operate on a publish-subscribe model.

Amazon SNS is a messaging service that enables the pub/sub model, allowing publishers to send messages to multiple subscribers.

Amazon CloudWatch is a monitoring service that collects and tracks metrics, logs, and events, not a messaging system.

AWS CloudFormation is an infrastructure as code service used for provisioning resources, not for message publishing or subscribing.