Which musical style depends on the performer to frequently change arrangement of simple tunes?

The answer is "Jazz". Jazz is a form of music wherein the musicians express themselves which makes them create or invent music on the spot. It is characterized by improvisation, syncopation and regular rhythm. Typically, they are played on instruments like horns, keyboards, bass, guitars, vocals and many others. This type of music signifies richness and beauty and has a wide range and diversity. Jazz is often called as the America's classical music. Its genre include acid jazz, big band, contemporary jazz, among many others.