Final answer:
The best theme represented by the dragon story is not making hasty judgments without all the information.
Step-by-step explanation:
The statement that best expresses a theme of the story where a knight confronts a snoring dragon is "It is a good idea to avoid making judgments before having all the information." This theme is highlighted by the knight's misconception about the dragon's intentions, based on the noises coming from its cave. When the knight learns that the noises were just the dragon snoring, it becomes clear that rushing to judgment can lead to misunderstandings. This narrative demonstrates that assumptions can often be incorrect, and one should seek full understanding before acting.