When we keep a jug under water to fill it, we hear a special kind of sound as the jug gets filled. Its reason is

The special sound we hear as a jug gets filled with water is due to resonance (Option C). As water fills the jug, the volume of the air column inside the jug decreases, continuously changing its natural frequency. This varying air column length means that at different points during the filling process, the natural frequency of the air column will momentarily match the frequency of the sound waves created by the filling water. When this happens, resonance occurs, which amplifies the sound waves. This amplified sound is what we hear as the distinctive noise associated with the filling jug. The phenomenon of resonance here results in the sound waves being significantly enhanced at specific frequencies, creating a noticeable change in pitch and volume as the jug continues to fill. This principle of resonance demonstrates how sound can interact with physical structures to produce distinct auditory effects.