Please do not take my word on this because i am no 100% sure but i think it is B because he is using a metaphor to compare his life to crystal stairs.
Answer:
Earth
Explanation:
I think it's Earth because it's wider than life and it lives longer than forever. It seems so simple that it's complicated. It travels around the sun but never leaves it's spot. I don't know about the other two stanza's but my guess would be Earth.