Answer:
The jazz style that features a front line of instruments improvising several melodies simultaneously while a rhythm section defines the pulse and harmony is known as "New Orleans jazz" or "Dixieland jazz."
Step-by-step explanation:
In this style, multiple instruments, such as trumpet, clarinet, and trombone, play individual improvised melodies, often in a collective improvisation known as "polyphony." The rhythm section, typically consisting of piano, banjo, bass, and drums, provides the underlying rhythmic foundation and harmonic support for the improvising front line.