The correct answer is C. Source.
The frequency of a sound wave is the number of waves that pass a given point in a given amount of time. It is measured in hertz (Hz), which is equal to one wave per second. The frequency of a sound wave is determined by the source of the sound. For example, a high-pitched sound has a higher frequency than a low-pitched sound.
Amplitude is the height of a wave. It is measured in meters. The amplitude of a sound wave does not affect its frequency.
Speed is the distance a wave travels in a given amount of time. It is measured in meters per second. The speed of a sound wave depends on the medium through which it is traveling. For example, sound travels faster through air than through water.
Medium is the substance through which a wave travels. Sound waves can travel through solids, liquids, and gases. The medium does not affect the frequency of a sound wave.