This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': 'Which one of the following statements regarding water re-absorption in the tubules is True? \nSelect and explain. \nA. The bulk of water re-absorption occurs secondary to Na+ re-absorption, B. Majority of facultative re-absorption occurs in proximal tubule, C. Obligatory re-absorption is ADH dependent, D. 20% of water is always re-absorbed irrespective of water balance', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Changes in sodium re-absorption significantly influence the re-absorption of water. Ref: Textbook of Medical Physiology By Guyton, 10th Edition, Page 299', 'role': 'assistant'}]