What best describes melody in a musical composition?

Melody in a musical composition is fundamentally a series of tones that are perceived as a single entity. This can be understood as the main theme of a piece of music. Melodies often convey emotion and are memorable, making them a crucial component of songs and instrumental pieces. They consist of a sequence of pitches that are organized rhythmically, leading to a recognizable musical line.

In contrast, while a sequence of musical notes played together forms the basis of chords, it’s not accurate in describing the melodic line itself. The underlying beat of a piece refers to the rhythm or tempo, which does not directly pertain to the melody. Lastly, harmonic accompaniment supports the melody but is not a description of the melody itself; it provides the context within which the melody is heard. Hence, defining melody as a series of tones is the most fitting description.