The kidneys in human beings are a part of the system for Nutrition, Respiration, Excretion, Transportation?

The correct option is C Excretion. Kidneys are the bean-shaped reddish-brown paired organs that serve in maintaining the fluid electrolyte balance and acid-base balance of the body through the process of urine formation. Excretion refers to the removal of metabolic waste from the body. This makes kidneys part of the excretory system. Nutrition refers to obtaining the food to meet the energy requirement for growth and development. Respiration refers to the process that allows entry of oxygen from air to blood and exit of carbon dioxide from blood to air. Transportation refers to the movement of materials, mainly nutrients and gases, from one organ to another.