Final answer:
A sound wave is produced by vibrating objects such as a speaker, tuning fork, or violin string, which set surrounding air molecules into motion. These waves are mechanical waves and need a medium to travel. They move at speeds relative to the molecular speeds of the medium and can exhibit phenomena like the Doppler Effect.
Step-by-step explanation:
A sound wave is produced by vibrating objects that set surrounding air molecules into motion. Therefore, the correct answer is b) Vibrating. Sound waves are mechanical waves and are different from light waves. Unlike light waves, sound cannot travel through a vacuum because it requires a medium to propagate. For example, when a speaker produces a sound, it oscillates, causing the air molecules around it to vibrate, and this disturbance creates the sound wave we hear. Similarly, a tuning fork or a violin string produces sound in the same manner; they cause air molecules to move through their vibrational motion.
The propagation of sound can be influenced by the medium it travels through. Disturbances like sound waves are transmitted at speeds that are related to the molecular speeds in that medium. Furthermore, the Doppler Effect illustrates how the frequency of a sound wave changes relative to a stationary observer when the source of sound is moving but does not affect the speed of sound itself.