The motion of a particle to and fro about its mean position is called:

Learn the meanings of vibration, frequency, and wavelength. Try to identify their units and clarify what they signify physically. Our response is the definition of the quantity that is comparable to our response.
Frequency is the number of times an event happens repeatedly in a certain amount of time. We can determine how often an event occurs by using frequency. Hertz is the unit of frequency (Hz). One whole event or cycle per unit of time is one Hz.
The largest deviation a particle may make from the vibration or oscillation's equilibrium location is known as the amplitude. Meters are the amplitude unit.

Think about a wave moving across a medium. A wave has crests and troughs. The wave's crests or peak is its highest point, while its trough is its lowest. The wavelength of a wave is the horizontal distance between two crests or troughs. Simply said, the wavelength is the measurement of how long a wave lasts over its whole cycle.
The motion of a particle relative to its equilibrium position is referred to as vibration. A particle is said to vibrate when it oscillates about its equilibrium location.

Hence, the correct answer is option C.