Final answer:
Without precise details, it is not possible to determine the exact two keys for clearing a DCS fault as it varies by system; typically it involves function keys or specific reset commands as outlined in the DCS manual.
Step-by-step explanation:
When dealing with a Distributed Control System (DCS) error, the specific keys to clear a fault can vary depending on the system's design and manufacturer. Generally, most control systems have a way to acknowledge and reset alarms or faults. However, without specific information on the make and model of the DCS in question, it's not possible to provide the exact key combination. Typically, operators might use function keys, designated 'Clear' or 'Reset' buttons, or a combination such as 'Ctrl + F' or 'Esc,' but this is not standard across all systems. Always refer to the specific DCS manual for the correct procedure.