A SysOps Administrator has been notified of an issue involving an Auto Scaling group with hundreds of instances. When the launch configuration is updated, the process for the Auto Scaling group is taking multiple nodes offline at the same time, which is impacting customers. The Application team uses AWS CloudFormation to update the application by changing a parameter to the version of code it wants to enable.
What can the Administrator do to limit the impact on customers while the update is being performed?

Answer options:

A.Edit the user data script to add a description of the instances in the Auto Scaling group and run AWS EC2 terminate-instances against the next oldest instance id.
B.Add the Update Policy attribute in Cloud Formation, and also enable the WaitOnResourceSignals property. Append a health check at the end of the user data script to signal CloudFormation that it was successful.
C.Convert the Auto Scaling group to many individual instances. Have the application team update one machine at a time in Cloud Formation.
D.Add a DependsOn attribute to the Auto Scaling group resource in Cloud Formation to depend on the Launch Configuration. Append to the user data script to signal the wait condition.

Correct Answer: B
The AWS Documentation mentions the following.
To specify how AWS CloudFormation handles replacement updates for an Auto Scaling group, use the AutoScalingReplacingUpdate policy. This policy enables you to specify whether AWS CloudFormation replaces an Auto Scaling group with a new one or replaces only the instances in the Auto Scaling group.
Options A and C are incorrect since this will still not prevent the changes of Cloudformation.
Option D is incorrect since the Autoscaling already depends on the Launch Configuration.
For more information on the update policy attribute, please visit the below URL-
https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-attribute-updatepolicy.html