Which of the following statements is untrue in regard to sound traveling in air?

a. as the distance from the earth increases, the sound wave intensity also decreases due to the lessening density. b. sound waves in the air are transverse and consist of compressions and rarefactions of air molecules. c. the area covered by the wave front increases as the wave advances, but the energy passing through a wave front in a unit of time decreases. d. during a single vibration of the diaphragm, molecules in the air near it will also complete one vibration.