Question

In which sentence does the underlined noun clause function as the object of a preposition?

Answer 1

The object of a preposition is a noun that comes after a preposition, so the sentence that has a noun clause after a preposition is

To play different styles of music in my band is what I would like to do

in: preposition

my band: the noun of the preposition

Answer 2

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.