Final answer:
The film that exclusively uses pre-existing music throughout its soundtrack is "Pulp Fiction", which employs a variety of previously released songs as opposed to an original film score.
Step-by-step explanation:
The film that exclusively uses pre-existing music throughout its soundtrack is d) "Pulp Fiction".
Unlike the scores crafted specifically for movies such as "Inception" and "The Shawshank Redemption", "Pulp Fiction" stands out due to its unique soundtrack, which brings together a variety of previously released songs.
Director Quentin Tarantino is known for his eclectic taste in music and skillful inclusion of these tracks to complement the scene in the film.
On the other hand, "Guardians of the Galaxy" also features a lot of pre-existing songs, but it is additionally accompanied by an original score.