Which in-depth approach is used when deploying defense in an industrial zone?
A. Use PLCs and control systems from multiple vendors in such a way that the process will become resilient for failures of one vendor.
B. Deploy two factor authentications for all operators which need to login remote while working from home.
C. Collect log files at a central location for easy back-up and encryption to provide privacy.
D. Create multiple zones in the industrial zone and protect / inspect traffic between the zones with firewalls and intrusion monitors.