The Trapped Traveler

You are stranded on a deserted island with three items: a mirror, a torch, and a can of gasoline. You need to signal a passing ship for rescue, but you can only use one item at a time. How do you use these items to get help?

Solution: Use the mirror to reflect the sunlight towards the passing ship. This creates a bright, focused beam that is more likely to be seen than a single flame from the torch. The gasoline is not needed for this solution and can be saved for another purpose, like warmth or cooking.