Which musical form does not restate previous material in a simple fashion but introduces unique contrasts?

Ternary form is characterized by its structure of A-B-A, where the first section (A) is stated, followed by a contrasting middle section (B), and then a return to the initial section (A). This form provides a clear contrast between the two sections, highlighting the unique musical ideas presented in the B section that differ from those in the A section. The return to the A section allows for a sense of familiar closure, but the essence of ternary form lies in the development and contrast introduced in the B section.

In contrast, binary form typically involves two contrasting sections that are often repeated, and rounded binary form establishes an initial A section that returns after a contrasting B section. Strophic form, on the other hand, repeats the same music for each verse or stanza, which does not facilitate the introduction of unique contrasts as effectively as ternary form does. Therefore, the ability of ternary form to showcase contrasting musical ideas is what makes it the best choice in this context.