Please help me fast. i dentify the underlined word in the sentence below as a preposition or an adverb. "He squealed as his sled raced down." down is underlined.

What is the most significant effect of waverly's two names? a. they allow her to be able to tell whether an american or chinese friend is calling her name based on which one she uses. b. they allow her to switch her identities like a double agent when she switches names. c. they distinguish between her two cultures and cause her to feel conflicted at times between her american and chinese selves. d. they distinguish between her family name and her official government papers name.