D. ¡Adiós!
Adiós means “goodbye” which is more final than just saying “bye” or “Hasta luego”
Hasta pronto and Hasta ahora both mean that you will see them soon
Hasta mañana means see you tomorrow
I’m pretty sure it’s “estamos pagando” if they are talking about the present time.
Answer:
I believe it is 3) to inform people of how to transport a bicycle on the subway
I hope this helps!