Your company operates an application consisting of an AWS CloudFormation stack that contains a load balancer, an Auto Scaling group of web servers, and an Amazon RDS instance. To save time and costs, you update the current test stack when testing minor changes, and create a new stack for major changes.
As part of the testing procedure of your application, each version needs to be registered once and only once with a Configuration Management Database (CMDB).
What cost-effective solution should you choose to perform this registration?

A. Use Auto Scaling Leader Node functionality to notify the registration application from the UserData script of a single Instance. Use the AWS CloudFormation cfn-hup helper application to receive template updates on the leader node, which then notifies the CMDB.
B. Define an AWS: :CloudFormation::CustomResource in the AWS CloudFormation template, with the application version as one of its properties. Modify the CMDB to subscribe to the resource's creation and update notifications.
C. Define an AWS::CloudFormation::HttpRequest in the AWS CloudFormation template, and configure it to notify the CMDB on stack creation and update.
D. Define an AWS::EC2::Instance resource in the AWS CloudFormation template that is configured to run a UserData script to notify the CMDB and then terminate itself on completion.