Which minor key has the same tonic as the major key but a different key signature?

• A. Relative minor
• B. Natural minor
• C. Harmonic minor
• D. Parallel minor

Answer: (D)

Parallel minor is the minor key built on the same root as a major key but with a different key signature. For example, C major and C minor share the tonic C, but C major has no flats or sharps while C minor typically uses three flats. This is why the same tonic but a different key signature points to the parallel minor. By contrast, a relative minor uses the same key signature as the major key but with a different tonic (for C major, that’s A minor), and natural/harmonic/melodic minor describe scale forms on that root rather than a distinct key signature change paired with the same root.