What part of speech does the adverbial clause bolded in the sentence below modify? Oliver decided to run until he reached the edge of town.

Select the best answer from the choice provided.
A.
adverb
B.
verb
C.
adjective
D.
noun

As a part of setting what time of year does the author use to demonstrate the theme in nothing gold can stay.nature’s first green is gold, her hardest hue to hold. her early leaf’s a flower; but only so an hour. then leaf subsides to leaf. so eden sank to grief, so dawn goes down to day. nothing gold can stay.