What Amazon EC2 feature allows for automatic scaling of applications?

The feature that facilitates automatic scaling of applications in Amazon EC2 is the Auto Scaling Group. This service automatically adjusts the number of EC2 instances in response to fluctuating demand, ensuring that applications have the right amount of compute resources at any given time. When the load on the application increases, the Auto Scaling Group can automatically launch additional EC2 instances to handle the increase. Conversely, when the demand decreases, it can terminate instances that are no longer needed to minimize costs.

This capability is crucial for maintaining application performance and optimizing resource usage without manual intervention. The Auto Scaling Group works in conjunction with metrics and rules defined by the user, often leveraging other AWS services for monitoring and scaling decisions.

Other options might support aspects of application scaling but do not provide the direct functionality of automatically adjusting the number of instances. Elastic Load Balancing helps distribute incoming application traffic among multiple targets, enhancing fault tolerance. CloudWatch monitors AWS resources and applications, providing alarms and metrics that can be used to trigger scaling actions. Amazon VPC is primarily focused on networking and resource isolation rather than scaling capabilities. Thus, the correct answer highlights the specific feature designed for automated resource management.