Question

melodies usually include pitches that are part of the songs ______.

Explanation:

In music theory (a sub - area related to Arts, specifically in the study of music which can be part of the broader Arts discipline), melodies are constructed using pitches that belong to the song's scale (or sometimes "key" or "harmony", but "scale" is a very fundamental and common answer here). A scale is a set of pitches in ascending or descending order that form the basis for the melody's notes. For example, in a major scale like C major (C, D, E, F, G, A, B), the melody of a song in C major will typically use these pitches.

Answer:

scale (or key, harmony - with "scale" being the most typical fundamental answer in basic music theory for this blank)