Assuming that in the last option 'whichever melody you create' is underlined, the correct answer is that one, the last sentence. Because this is the only sentence in which 'to' is used as a preposition, in 2 and 3 there are no prepositions, and in 1 'to' is a part of an infinitive phrase.
Answer:
The narrator's point of view allows the reader to develop a better understanding of the author's opinion. The narrator's point of view allows the reader to understand the perspectives of all of the characters.
The author is trying to portray that all parts are important even though some may come smaller or larger than other. Nothing could happen as planned without the smaller of bigger parts