Final answer:
Artificial respiration should be started immediately on an unconscious and not breathing train operator who has suffered an electric shock from the third rail.
Step-by-step explanation:
Artificial respiration should be started immediately on a train operator who has suffered an electric shock by coming in contact with the third rail if he is unconscious and not breathing. When someone is unconscious and not breathing, it means that their heart has stopped and their body is not receiving oxygen. Artificial respiration, or CPR, can help to restore breathing and circulation until medical help arrives.