You have configured the following AWS services in your organization - Auto Scaling group, Elastic Load Balancer, and EC2 instances. You have been requested to terminate an instance from the Autoscaling Group when the CPU utilization is less than 30%. How can you achieve this.

Answer options:

A.Create a CloudWatch alarm to send a notification to SQS. SQS can then remove one instance from the Autoscaling Group.
B.Create a CloudWatch alarm to send a notification to the Auto Scaling group when the aggregated CPU utilization is less than 30% and configure the Auto Scaling policy to remove one instance.
C.Create a CloudWatch alarm to send a notification to the ELB. The ELB can then remove one instance from the Autoscaling Group.
D.Create a CloudWatch alarm to send a notification to the admin team. The admin team can then manually terminate an instance from the Autoscaling Group.

Answer - B
The AWS Documentation mentions the following
You should have two policies, one for scaling in (terminating instances) and one for scaling out (launching instances), for each event to monitor. For example, if you want to scale out when the network bandwidth reaches a certain level, create a policy specifying that Auto Scaling should start a certain number of instances to help with your traffic. But you may also want an accompanying policy to scale in by a certain number when the network bandwidth level goes back down
For more information on the scaling plans,please see the below link:
http://docs.aws.amazon.com/autoscaling/latest/userguide/scaling_plan.html