What defines notes that are moving by step?

The definition of notes that are moving by step pertains specifically to the difference in pitch between two consecutive notes of a scale. This movement is characterized by a progression from one note to the very next note in a sequence, which is fundamental in creating melodic lines. In traditional Western music, this means that if you move from C to D, for instance, you are moving by step due to being adjacent notes within the scale.

By contrast, the other options describe different musical concepts that do not relate directly to the idea of moving by step. The option that discusses non-consecutive notes refers to leaps or skips in the melody, which involve larger intervals than moving stepwise. Similarly, the repetition of the same note does not involve any change in pitch at all, and the combination of two notes played simultaneously pertains to harmony rather than melodic movement. Therefore, the correct response focuses solely on the immediate succession of pitches that defines stepwise motion in music.