What characteristic is typically seen in the exposition of an eighteenth-century composition written in sonata form?

In an eighteenth-century composition written in sonata form, a key characteristic of the exposition is that the secondary themes appear in a contrasting key. This is fundamental to the structure of sonata form, which typically includes three main sections: the exposition, development, and recapitulation.

During the exposition, the primary theme is introduced in the home key, setting a tonal foundation. The secondary themes, which follow, are usually presented in a different, contrasting key—often the dominant key if the piece is in a major key—and this contrast helps create tension and interest. This shift between primary and secondary themes is crucial for establishing the thematic and tonal relationships that will be explored in the subsequent development section.

The other options do not accurately reflect the standard practices of sonata form in the eighteenth-century. For instance, while melodies may exhibit counterpoint, they are typically not complex to the extent described in the context of an exposition; rather, clarity and thematic distinction are prioritized. The primary theme is not repeated verbatim in the exposition, as it sets up a contrast with the secondary theme. Additionally, the exposition is characterized by a clear thematic structure, which is essential for the subsequent development and recapitulation. Thus, the contrasting key of the secondary themes is