I would say D.
You can eliminate C, as he says it doesn't matter which road he walks.
You can also eliminate B, as there's no mention of water
That leaves you with A and D, but it couldn't be A as there's no one else there for him to be thinking of. He state's "he was alone in this world of A.D. 2053..." and that also foreshadows time travel or maybe a second dimension. Sounds like a fun story though.
