Answer:
C. The number of waves that pass a particular point in a unit of time.
Step-by-step explanation:
The number of waves that pass a fixed point in unit time and the number of cycles or vibrations undergone during one unit of time by a body in periodic motion is called as frequency.
A body in periodic motion is said to have undergone one cycle or one vibration after passing through a series of events or positions and returning to its original state.
The unit of frequency is Hertz.