SCADA systems are used to monitor and control industrial processes, such as those used in electricity generation. Disabling the safety instrumented system and deploying ransomware on the engineering workstation could prevent the engineers from properly maintaining the SCADA equipment, potentially leading to operational issues and disruptions.
It is not likely that a turbine would overheat and cause physical harm (option A) as a result of this attack. The engineers may need to go to the historian (option B) to retrieve historical data for troubleshooting purposes, but this would not be a direct consequence of the attack. Data would not be exfiltrated through the data diodes (option D) as a result of this attack, as data diodes are unidirectional network connections that prevent data from being transmitted in the opposite direction. Data diodes are often used to isolate critical systems from external networks in order to prevent data exfiltration.