Answer.(C)
Kidney in human being is excretory organ
Responsible for filtering waste and excess water from the blood to produce urine. They also play a crucial role in maintaining electrolyte and fluid balance, regulating blood pressure, and producing hormones like erythropoietin to stimulate red blood cell production.

The correct answer is c. excretion. Kidneys are the primary organs responsible for filtering waste products from the blood and excreting them as urine.