If you are referring to like a crowd that means that they should understand where your coming from ya know.
C is the answer you are looking for. A common idea isn't a moral, the generalization is the Main Idea, but not quite the moral. The thought of the characters almost never have the moral in them. Therefore, C is your answer.
The 7 critical thinking habits of the mind include...
Open-minded, truth seeking, analytical, systematic, confident in reasoning, inquisitive, and judicious.