Answer:
B. A different version of a piece.
In music, an arrangement refers to a new version of a piece of music that has been modified from its original form. The arrangement can involve changes in instrumentation, harmony, melody, rhythm, or other musical elements, and it can be created for any type of ensemble or performer, from soloists to large orchestras. Arrangements can also be created for a different style or genre, such as a jazz or rock version of a classical piece, or vice versa.