In music, what defines a tonic minor scale?

A tonic minor scale is defined by its relationship to the tonic major scale, specifically having the same tonic note but differing in the pattern of whole and half steps that create its minor tonality. In this context, the tonic serves as the root note of both the major and minor scales; for instance, in the key of A minor, the tonic is A, which also functions as the tonic for the A major scale.

This relationship is foundational in Western music theory, as it allows composers and musicians to explore different emotional qualities while still maintaining a connection through shared tonics. The minor scale, characterized by its unique intervals, results in a darker, more introspective sound compared to its major counterpart, but the shared tonic note anchors it.

The other options do not accurately represent the tonic minor scale. For instance, a minor key one step below a major scale refers to a different concept entirely and does not represent the tonic minor's relationship to its major form. Similarly, describing a major key with the same tonic as a minor scale conflates the distinctions between major and minor tonalities, while claiming that it's the relative major key of the minor scale could mislead one about the unique characteristics of the tonic minor scale itself.