This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Excretory System (Kidney, Bladder) Acid-Base Balance, Subject name: Physiology
[{'content': 'In the presence of ADH, greatest fraction of the filtered water is reabsorbed from: \nSelect and explain. \nA. PCT, B. Loop of Henle, C. DCT, D. Collecting duct', 'role': 'user'}, {'content': 'Answer: A \nExplanation: 65%-70% of the filtered water is reabsorbed from the PCT. This is called obligatory water reabsorption and occurs irrespective of the osmolarity of ECF. In the complete absence of ADH action, 88% of the filtered water is reabsorbed from various segments of nephron. 10%-12% water is reabsorbed from collecting duct under the maximum action of ADH. This is called facultative water reabsorption. Water reabsorption from the collecting duct is determined by osmolarity of ECF.', 'role': 'assistant'}]