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 best answer to the question that is being stated above would be the sentence that is numbered one (1): 'When it comes to fiction, there are many genres'. The next sentences are only subtopics and only support the main idea that are lots of genres for fiction.
There's a good answer to that question.
This is right because I don't really know if there're is a real word.