Which of the following organ never helps in oxygenation of blood in any vertebrate, at any stage of their life?

Step-by-step solution

Vertebrates such as amphibians have 3-chambered heart, muscular, myogenic heart with two atria and single ventricle. In amphibians, the left atrium receives oxygenated blood from the gills/lungs/skin and the right atrium gets the deoxygenated blood from other body parts. In amniota group, i.e. reptiles, birds and mammals, respiration is mainly pulmonary, in fishes it is through gills. In vertebrates, the kidney is mainly involved in osmoregulation and excretion.