Which mode is major scale with lowered seventh?

• A. Ionian
• B. Lydian
• C. Aeolian
• D. Mixolydian

Answer: (D)

In modal thinking, the difference between modes comes from how one pitches are altered compared to the major scale. The defining change here is lowering the seventh degree of a major-scale set of notes. When you take the major scale and flatten its seventh, you land on the Mixolydian mode. For example, starting on C, the major scale would be C D E F G A B. Lower that seventh to B♭ and you get C D E F G A B♭, which is Mixolydian. This contrasts with Ionian (the unaltered major scale with a natural seventh), Lydian (raised fourth), and Aeolian (the natural minor with a flat third, sixth, and seventh relative to major). So the mode defined by a major scale with a lowered seventh is Mixolydian.