You created a pipeline that can deploy your source code changes to your infrastructure in instance groups for self-healing. One of the changes negatively affect...

You created a pipeline that can deploy your source code changes to your infrastructure in instance groups for self-healing. One of the changes negatively affects your key performance indicator. You are not sure how to fix it, and investigation could take up to a week.
What should you do?

A. Log in to a server, and iterate on the fox locally B. Revert the source code change, and rerun the deployment pipeline C. Log into the servers with the bad code change, and swap in the previous code D. Change the instance group template to the previous one, and delete all instances