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
What is the percentage of water in adult human being? 
Select and explain. 
A. 40%, B. 50%, C. 60%, D. 70%
C: 60%
Answer: C: 60% 
Explanation: In the average young adult male, 18% of the body weight is protein and related substances, 7% is mineral, and 15% is fat. The remaining 60% is water. Ref: Ganong's Review of Medical Physiology 23rd edition, Chapter 1.