What feature does Amazon ECS with autoscrolling utilize to adjust container instances?

Amazon ECS (Elastic Container Service) with autoscaling leverages integration with EC2 Auto Scaling to adjust container instances automatically based on demand. This capability allows ECS to dynamically adjust the number of EC2 instances in a cluster as application demands increase or decrease, ensuring that there are always enough resources available to handle the current workload efficiently.

By utilizing EC2 Auto Scaling, ECS can monitor metrics and automatically scale out (add instances) or scale in (remove instances) of container instances based on predefined policies, such as CPU utilization or memory usage. This means that you can maintain optimal performance while controlling costs by only using resources that are necessary at any given time.

The other choices do not accurately reflect how ECS manages container instances in the context of autoscaling. Manual scaling requires direct user intervention, which does not provide the efficiency and responsiveness that automated solutions do. Fixed resource allocation for containers contradicts the principle of autoscaling, which focuses on flexibility and dynamic resource management. Dynamic content handling via Lambda pertains to serverless computing and does not relate to container management with ECS.