Music appreciation playing large groups of adjacent notes on the piano in a percussive manner creates a sound called a/an                a.  tone cluster.      b.  chordophone.      c.  gamelan.      d.  aleatory.

In my opinion, the correct answer is A. tone cluster. A tone cluster is comprised of at least three adjacent notes (piano keys), but it can also have a lot more adjacent notes. This effect has been used frequently by modern composers, from the beginning of the 20th century onward, but it has also been employed in jazz. Their most basic characteristic is dissonance.

One is symmetrical, one is radial.