A Company Has a Mission-Critical Application on AWS That Uses

A company has a mission-critical application on AWS that uses automatic scaling. The company wants the deployment lifecycle to meet the following parameters: • The application must be deployed one instance at a time to ensure the remaining fleet continues to serve traffic. • The application is CPU intensive and must be closely monitored. • The deployment must automatically roll back if the CPU utilization of the deployment instance exceeds 85%. Which solution will meet these requirements?

A) Use AWS CloudFormation to create an AWS Step Functions state machine and Auto Scaling lifecycle hooks to move to one instance at a time into a wait state. Use AWS Systems Manager automation to deploy the update to each instance and move it back into the Auto Scaling group using the heartbeat timeout.
B) Use AWS CodeDeploy with Amazon EC2 Auto Scaling. Configure an alarm tied to the CPU utilization metric. Use the CodeDeployDefault.OneAtAtime configuration as a deployment strategy. Configure automatic rollbacks within the deployment group to roll back the deployment if the alarm thresholds are breached.
C) Use AWS Elastic Beanstalk for load balancing and AWS Auto Scaling. Configure an alarm tied to the CPU utilization metric. Configure rolling deployments with a fixed batch size of one instance. Enable enhanced health to monitor the status of the deployment and roll back based on the alarm previously created.
D) Use AWS Systems Manager to perform a blue/green deployment with Amazon EC2 Auto Scaling. Configure an alarm tied to the CPU utilization metric. Deploy updates one at a time. Configure automatic rollbacks within the Auto Scaling group to roll back the deployment if the alarm thresholds are breached.