The main idea doesn't explain in detail why it is the main idea. It doesn't prove that it is the main idea, it only states so.
The correct answer is: It is easier to fix organizational flaws when an essay is in the outline phase.
Writing an outline will make it easier for you to organize your ideas therefore, it will still work when you have a short amount of time to write. During the outline phase, you are organizing ideas so details gathered are important. Lastly, revisions are made after the writing stage.
