You have been tasked with deploying a scalable distributed system using AWS OpsWorks. Your distributed system is required to scale on demand. As it is distributed, each node must hold a configuration file containing the hostnames of the other instances within the layer. How should you configure AWS OpsWorks to manage scaling this application dynamically?

Answer options:

A.Create a Chef Recipe to update this configuration file, configure your AWS OpsWorks stack to use custom cookbooks, and assign this recipe to the Configure LifeCycle Event of the specific layer.
B.Update this configuration file by writing a script to poll the AWS OpsWorks service API for new instances. Configure your base AMI to execute this script on Operating System startup.
C.Create a Chef Recipe to update this configuration file, configure your AWS OpsWorks stack to use custom cookbooks, and assign this recipe to execute when instances are launched.
D.Configure your AWS OpsWorks layer to use the AWS-provided recipe for distributed host configuration, and configure the instance hostname and file path parameters in your recipes settings.

Answer – A
Please check the following AWS DOCs which provides details on the scenario. Check the example of "configure".
https://docs.aws.amazon.com/opsworks/latest/userguide/workingcookbook-events.html
You can use the Configure Lifecycle event.
This event occurs on all of the stack`s instances when one of the following occurs:
An instance enters or leaves the online state.
You associate an Elastic IP address with an instance or disassociate one from an instance.
You attach an Elastic Load Balancing load balancer to a layer or detach one from a layer.
Ensure the Opswork layer uses a custom Cookbook.
For more information on Opswork stacks, please refer to the below document link: from AWS
http://docs.aws.amazon.com/opsworks/latest/userguide/welcome_classic.html