The answer to this is A. There will be instances when you would need to transfer a certain portion of your document to another portion of the document. Instead of having to do everything words per word, you can just cut and paste. The best part is that the cut and paste button can be seen easily.
You can even include it in such a way that it can be seen immediately. It will depend on you how you are going to utilize this as well as the other buttons that you can see in the home tab. What tab do you find yourself using the most?