Okay so, first of all, a memoir is a historical account or a biography. an Autobiography is an biography written by the person it is about, and expository is the intention to explain something, informational is providing information or facts, and a technical is involving sciences. Using this information you can make your prediction, but in my opinion, informational and expository both seem to fit well. you can pick off your own judgement or you can go off mine, I think this is an expository.
Good luck and I hope I helped you!