The central idea would be that even though Edison made lots of horrible inventions and mistakes, without him not giving up and continuing we wouldn’t have things we use everyday. So basically keep going and don’t give up.
D would be your best answer. Because if you were going to be working on a test your goal is to get things done as quickly and efficiently as possible chances are the answers going to be in that line or a line before or after it not the entire section. Especially on standardized test’s such as the SAT or AP
It wraps the story up and makes it have a positive ending!