The Correct answer is "D".
John Cage is known for introducing the concept of a "prepared piano". Which consists of placing different objects o or between the strings in order to alter the original sound caused by them and create new sounds. He first applied this while writing the music for the dance "Bacchanale", in 1938. Cage believed that it was possible to "place in the hands of a single musician the equivalent of an entire percussion orchestra".
Answer:
If you're asking for specific element, it would be copper. In an overall sense, it is metal.
