Final answer:
The rhyme scheme in "Up-Hill" supports the presence of two distinct voices by alternately rhyming lines and utilizing indents, thereby creating a sense of unity while distinguishing the dialogue between them.
Step-by-step explanation:
The rhyme scheme in "Up-Hill" by Christina Rossetti does indeed help establish two distinct voices within the poem, and the correct answer is a) It creates a sense of unity. The alternating rhyme scheme, often noted with letters representing the sounds like 'a b a b c d d ce fe f', and the distinct refrain at each stanza's end are stylistic choices that unite the poem while also distinguishing the conversational voices. Each indent in the poem is strategically placed to underscore the rhyming lines, emphasizing the back-and-forth nature of a dialogue between the querying self and the responding self, signifying, respectively, the questioning and the assurance that comes in the form of responses.
Rhyme schemes in poetry are often utilized to give structure and rhythm to the verse, and in this specific case, they underscore the dialogue between two speakers. The alternating indents and the constant refrain serve as additional cues for the reader to differentiate between the two voices.