Who Is An Impostor?
Riddle: Your spaceship lands on a foreign planet. A stranger in his workout clothes greets you to the entrance of the base. You go inside the base and wait for it to depressurize before removing your space suit. But before you get a chance to remove it, you get a message that someone at the base is an impostor. Who could it be–a man who covers his face because he has a sunburn, a woman with flaky patches all over her skin, or the stranger you saw earlier?
Answer: The stranger you saw earlier is an impostor because a human who is not wearing a spacesuit cannot survive outside of the base in the foreign planet's atmosphere, but this stranger somehow survived without his spacesuit.
Source: https://www.riddles.com/index.php/11439
