Correct Option: A

Earthworms have no skeleton but during burrowing, anterior end becomes turgid and acts as a hydraulic skeleton. It is due to coelomic fluid. The coelom is filled with an alkaline milky coelomic fluid. This coelomic fluid contains water, salts, proteins and 4 types of cells namely amoebocytes, mucocytes, circular cells and chloragogen cells.