What defines a harmonic minor scale?

A harmonic minor scale is specifically characterized by its raised seventh scale degree in comparison to the natural minor scale. This alteration, the raising of the seventh note, creates a leading tone that provides a stronger pull to the tonic when ascending, which is essential for establishing harmony and resolution in music. This scale is particularly important in the context of Western classical music and is often used to create tension and facilitate modulation.

The other options do not accurately describe the harmonic minor scale. For example, a major scale with a lowered sixth degree relates more to the melodic minor scale and does not capture the essence of the harmonic minor. The inclusion of all twelve pitches and the repetition of each note in the octave describe concepts that are unrelated to the specific structure of the harmonic minor scale, which is distinctly defined by its unique intervals. Thus, the correct choice effectively highlights the critical characteristic that differentiates the harmonic minor from other scales.