The correct option is C. feed on organic material falling from above.
Some sea organisms inhabit shallow or deep sea floor or sometimes remain partially buried beneath it.
One such example is sea cucumbers. Sea cucumbers or similar organisms feed on minute aquatic animals or tiny particles like algae or other waste materials and gather them with tentacles. These organisms may also prey on fish or other sea animals. The organic detritus falling from the upper layers of water column is a continuous shower. The planktons, sand, soot, diatoms and inorganic dust and are consumed.