Which AWS service meets this requirement?

Explanations:

AWS Auto Scaling is used for automatically adjusting the number of EC2 instances in response to demand. It does not facilitate message passing between applications.

Elastic Load Balancing distributes incoming application traffic across multiple targets, such as EC2 instances. It does not provide a messaging service for communication between applications.

Amazon Simple Queue Service (Amazon SQS) is a fully managed message queuing service that enables decoupling and scaling of microservices and distributed systems. It allows applications to send, store, and receive messages reliably.

Amazon Kinesis Data Streams is designed for real-time data streaming and analytics. While it allows applications to process data in real-time, it is not primarily used for messaging between applications like SQS.