A Company's Application Is Running on Amazon EC2 Instances in an Auto

Multiple Choice

A company's application is running on Amazon EC2 instances in an Auto Scaling group. A DevOps engineer needs to ensure there are at least four application servers running at all times. Whenever an update has to be made to the application, the engineer creates a new AMI with the updated configuration and updates the AWS CloudFormation template with the new AMI ID. After the stack finishes, the engineer manually terminates the old instances one by one, verifying that the new instance is operational before proceeding. The engineer needs to automate this process. Which action will allow for the LEAST number of manual steps moving forward?

A) Update the CloudFormation template to include the UpdatePolicy attribute with the AutoScalingRollingUpdate policy.
B) Update the CloudFormation template to include the UpdatePolicy attribute with the AutoScalingReplacingUpdate policy.
C) Use an Auto Scaling lifecycle hook to verify that the previous instance is operational before allowing the DevOps engineer's selected instance to terminate.
D) Use an Auto Scaling lifecycle hook to confirm there are at least four running instances before allowing the DevOps engineer's selected instance to terminate.