Which form consists of two related but contrasting sections, labeled as AA'?

Binary form is characterized by its two related but contrasting sections, typically referred to as A and B. In the case where one of the sections returns with some variation, it may be described as AA', which indicates that the first section has been altered in some way during its recurrence. This structure emphasizes the contrast between the two sections while also allowing for a nuanced return to familiar material. This form is prevalent in instrumental music and highlights the composer's ability to create varied textures and themes within a coherent framework. Other forms mentioned, such as rounded binary, ternary, and strophic, have distinct characteristics that differentiate them from binary form. Rounded binary includes a return to the A section after B, ternary form presents three distinct sections (ABA), and strophic form consists of repeated music for verses or stanzas, rather than contrasting sections.