Cause its frickin english
Answer:
Agnostic means to believe in a higher power, but not one that necessarily coincides with a specific religion. It is not atheism and it is not theism. It is believing that there is something there (that could be a god(s)), so to speak.
Both fleeting and d. transient mean lasting only for a little bit or a momentary event. (ex. the scent of chocolate when you walk by a chocolate factory)