Final answer:
When the victim is already deceased, there is nothing that can be done to preserve their organs. CPR should only be administered when there is a chance of preserving life.
Step-by-step explanation:
When you arrive at a scene of a motor vehicle collision and discover that the victim, who is an organ donor, is already deceased, there is nothing you can do to preserve their organs. Attempting CPR at this point would not be effective and would not increase the chances of organ harvesting. CPR should only be administered when there is a chance of preserving life.