Two girls were walking in the forest. It started raining very hard, so they took shelter in a nearby hut. When it stopped raining, they went out to look for food. The first girl went straight, and the second girl went left. The first girl found an apple tree, so she took a bite out of an apple. She was turned into an apple tree. The second girl didn't find anything, so she went to find her friend. When she got to the apple trees, a voice said, "Your friend has been turned into an apple tree. You have one guess to figure out which one is her, or she will be stuck as a tree forever." The second girl immediately knew which tree was her friend. How did she know?
