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
The mechanism by which water is reabsorbed from proximal convoluted tubule is 
Select and explain. 
A. Active transport, B. Passive transport, C. Facilitated diffusion, D. Osmosis
D: Osmosis
Answer: D: Osmosis 
Explanation: Maximum of filtered water (60-70%) is reabsorbed in the proximal tubule, with or without Vasopressin. This is independent of the fluid and electrolyte status of the body and is caused by the osmotic gradient created by Na+ reabsorption.