Question

{"given":"Identify the type of functional adult kidney present in a rabbit (a mammal).","key_observation":"Vertebrate kidneys evolved in three stages — pronephros, mesonephros, and metanephros — with metanephros being the most advanced and the functional adult kidney in all amniotes (reptiles, birds, and mammals).","option_analysis":[{"label":"(A)","text":"Pronephros","verdict":"incorrect","explanation":"Pronephros is the most primitive kidney, functional only in larvae of some fish and amphibians. It is never the functional adult kidney in mammals."},{"label":"(B)","text":"Metanephros","verdict":"correct","explanation":"Metanephros is the most advanced type of kidney, divided into cortex and medulla. It is the functional adult kidney in reptiles, birds, and mammals, including rabbits and humans."},{"label":"(C)","text":"Mesonephros","verdict":"incorrect","explanation":"Mesonephros is the functional adult kidney in fish and amphibians (anamniotes). In amniotes like rabbits, it functions only transiently during embryonic development."},{"label":"(D)","text":"Opisthonephros","verdict":"incorrect","explanation":"Opisthonephros is the adult kidney found in most anamniotes (fish and amphibians). It is not present in mammals like rabbits."}],"answer":"(B)","formula_steps":[]}