A. Set up an AWS Lambda function that will initiate a run instance event and check for the required tags. Configure the function to prevent the launch of EC2 instances if the tags are missing.
B. Set up an AWS Config rule to monitor for EC2 instances that lack the required tags.
C. Set up a service control policy (SCP) that prevents the launch of EC2 instances that lack the required tags. Attach the SCP to the organization root.
D. Set up an Amazon CloudWatch alarm to stop any EC2 instances that lack the required tags.