Gregorian chant uses which scale system?

• A. Eight church modes
• B. Chromatic scales only
• C. Twelve-tone system
• D. Pentatonic scale

Answer: (A)

Gregorian chant is organized around a modal framework, specifically eight church modes. Each chant centers on a final pitch and uses a diatonic scale with characteristic patterns that define its mood, with four authentic modes and four plagal forms. This approach is different from later tonal systems built on major/minor keys, chromatic scales, or the twelve-tone method, and it isn’t based on a pentatonic scale. So the eight church modes best describe how Gregorian chant organizes pitch.