What is group structure?

Amplitude is: a. the number of waves in a certain amount of time. b. the distance between the top or bottom of a wave and the center of the wave. c. the noise floor acceptable in recording. d. the distance between two identical points on a wave.

This painting is by james whistler, and is entitled, symphony in blue and pink. what is the subject matter of this piece?

Why you appreciate/love your chosen piece of music