TOEFL Listening: ETS-TOEFL听力机经 - PXRO4F1F_OV9NZ_3P$

Why does the professor mention parades and park concerts? A. To find out how far the pianos are played out in the open B. To show how the piano was sometimes replaced by other instruments C. To support the point that Ragtime music was mostly played in public D. To give an example of public concert during the Ragtime era