The choices are: Keep people safe, Find the teacher, Serve the nameless one, Kill the nameless one, To be left alone, Don't tell. If you want to change your choice you need do delete the current persistent file and place che old persistent file, be aware that doing so may break the game. For now there isn't a clear check, the only thing that you can know is if you sided with him, against him or remained neutral, based of what he tells you during the nightmare in the plains of death.