What led to the birth of polyphonic music

D. An effort to revolutionize the plain chant.

Explanation: I got this right on Edmentum.

First of all you would die.   do not try this at home but back to the question.   there are six parts of the sun.   from the outside to the inside: corona, chromoshpere, photosphere, convective zone, radiative zone, and the core.   then use the dictionary or reliable sources such as wikipedia to find out what they do.   good luck.