Identify the term that indicates the absence of sound

What is “pitch”?

a. a short, distinctive figure b. the speed of the beat c. the relative position, high or low, of a musical sound d. the tonal center of the scale e. the concluding part of a musical phrase

What are three major conclusions about the history of twentieth-century music that can be drawn from Stravinsky's conversion to serial and twelve-tone composition?

What will be an ideal response?