Question: is armin from attack on titan a titan?
Answer: Armin became a Titan after Levi decided that he will be the one to live, instead of the other option that was Erwin Smith. This was after a conflict between both Mikasa and Eren against Levi and Floch, with both Mikasa and Eren wanting to save Armin, while Floch, who brought a dying Erwin to them, wanted to save Erwin.