Ternary form is most clearly represented by which pattern?

• A. ABB
• B. ABA
• C. ABC
• D. AAB

Answer: (B)

Ternary form is a three-part design where you present a theme, introduce a contrasting middle section, and then return to the original theme. The return of the initial material after the middle section creates that balanced, tripartite feel. That’s why the pattern ABA is the best representation: it starts with A, moves to B as a contrasting interlude, and then brings back A to close. The other patterns don’t achieve this return to the first material—ABB continues with a variation of the first idea and then nothing repeats the initial A; ABC has three unrelated sections with no bringing back of the initial theme; AAB repeats the first idea without the contrasting middle in between. So ABA captures the classic three-part structure that defines ternary form.