What is one key characteristic of jazz as a musical genre?

Jazz is distinguished by its emphasis on improvisation, which allows musicians to create spontaneous variations on a theme or melody during a performance. This characteristic fosters a unique and personal expression within each performance, making every rendition of a piece distinct from any other. Improvization in jazz highlights the individual creativity of performers and often leads to dynamic interactions between musicians as they respond to each other's playing in real-time.

In contrast to this characteristic, options like strict adherence to written music, exclusive use of orchestral instruments, and only vocal performances do not align with the fundamental nature of jazz. Jazz musicians typically use written charts as guides rather than strict scores, and the genre often incorporates a broad range of instruments beyond orchestral ones, including saxophones, trumpets, pianos, and drums, among others. Additionally, while vocal performance is an essential aspect of jazz, the genre is not limited to this form; it includes instrumental performances that are equally important to its development and expression.