The correct option is D Excretory system
∙ After digestion of food, the undigested material or by-products are expelled in two ways.
∙ Substances such as salts, urea, etc., are expelled from the body via skin or kidneys. Which together form the excretory system.
∙ Complete digestion of carbohydrate, proteins and fat occurs in small intestine, followed by their absorption. The undigested food (faeces) is then expelled through rectum of large intestine by the process of defecation.