What does the frequency of a wave motion refer to?

The frequency of a wave motion specifically refers to how often a complete wave cycle occurs in a given time frame, typically measured in seconds. Hence, it indicates the number of complete waves that pass a specific point in one second. Frequency is an essential property of waves as it directly affects characteristics such as pitch in sound waves and color in light waves.

In contrast, the amplitude of a wave relates to the height of the wave, which reflects the wave's energy but does not quantify how many cycles occur over time. The total energy of the wave is dependent on both the amplitude and frequency, but it is not synonymous with frequency. The speed of the wave pertains to how quickly a wave travels through a medium, which can be affected by frequency but is a distinct concept that does not define what frequency measures. Thus, option C accurately captures the essence of frequency in wave motion.