Circle of Fifths is best described as keys or tonalities ordered by ascending (for sharp keys) or descending (for flat keys) intervals of a fifth.

• A. Keys or tonalities ordered by ascending (for sharp keys) or descending (for flat keys) intervals of a fifth
• B. A method of tuning instruments
• C. A type of cadence
• D. A scale degree sequence

Answer: (A)

The circle of fifths is a way to organize keys by their key signatures according to steps of a perfect fifth. Moving clockwise from C major advances by a fifth each time, so you add one sharp to the key signature (G major has one sharp, D major has two, A major three, and so on). Moving counterclockwise goes down by a fifth (or up a fourth), adding one flat each step (F major has one flat, Bb major two, Eb major three, etc.). This layout also helps you see related keys and how modulation works, since keys with close positions share many common tones. It’s not about tuning instruments, cadences, or scale-degree sequences.