A customer wants to deploy a large number of 3-tier web applications on Compute Engine.
How should the customer ensure authenticated network separation between the different tiers of the application?

A. Run each tier in its own Project, and segregate using Project labels. B. Run each tier with a different Service Account (SA), and use SA-based firewall rules. C. Run each tier in its own subnet, and use subnet-based firewall rules. D. Run each tier with its own VM tags, and use tag-based firewall rules.