Apiece of music where one part echoes or imitates another part is known as what

What is the most famous racetrack in america?

Jazz evolved slowly from a number of different musical sources..true or false

Sorry about the calculator and me asap me asap because for real like some no one answers question one for me so that's why i'm posting them over to that way someone can at least answer number two or one for me if you do you so much if you do it would be a complete big blessing to me