question_answer 43)

                  Sound travels in air, if (a) particles of medium travel from one place to another (b) there is no moisture in the atmosphere (c) disturbance moves (d) both particles as well as disturbance travel from one place to another

Answer:

  (c) Sound travels in air if disturbance moves. As during the propagation of sound waves, particles only vibrates in its own position and disturbances created by the vibration of particle moves from one place to other.