Correct Option: D

Splanchology is the scientific study of the viscera and its organs. It studies the characteristics and structure of the visceral system of an animal. It is the study of viscera, which are the organs situated in the thoracic, abdominal and pelvic cavities of the body, and are associated with pleura and peritoneum. There are four major systems identified in the viscera according to their functions, and they are the digestive system, the respiratory system, the urinary system, and the reproductive system. These four major systems are to process bodily intakes for metabolism such as nutrients and oxygen from surrounding and to remove the wastes from the body. One last function of the viscera is to ensure the survival of the species as a whole by conducting the process of reproduction.