Which AWS service or resource will meet these requirements?

Explanations:

Amazon CloudWatch is a monitoring and observability service that provides data and insights into AWS resources and applications. While it helps in tracking performance, it does not directly manage or scale EC2 instances to meet demand or cost requirements.

An Application Load Balancer distributes incoming application traffic across multiple targets, such as EC2 instances. It helps improve application availability and fault tolerance but does not inherently manage scaling or cost efficiency for EC2 instances.

AWS Batch enables developers to run batch computing jobs but does not provide features for managing the scaling of EC2 instances for steady and predictable performance or cost optimization. It focuses more on job scheduling and resource allocation for batch jobs.

Amazon EC2 Auto Scaling automatically adjusts the number of EC2 instances in response to demand, ensuring that the right resources are available at the right time. This service helps maintain steady performance while optimizing costs by scaling resources up or down based on utilization.