The answer to this is letter D. The fact that it is already the third phase means that you are done with the different things that you have to write. You have written the different portions of the writing content and you are now making sure if all the details are correct.
It is best if you would improve the content and the structure based on what you think will make everything better. There are times when you may feel that the message that you have sent is not too clear. This phase will allow you to make the necessary changes.