I would say the third one but i am not so sure about it
Explanation:
Every author and writer has to develop the main idea of the text in one of the sections and the first section is often the one who is showing it. It can also be at the end of the story.
- Author can discuss about opposite things of the story, some of the opinions, point of views of the characters, by giving some specific details and many more.
The central idea will focus on what is the most important topic of the story and it has ability to control the direction of the writing.
Think outside the box, and most stories come together better when you come up with a plot first.