This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Circulation: Circulatory Shock and Its Treatment, Subject name: Physiology
To cause hemorrhagic shock, least volume of blood loss should be: 
Select and explain. 
A. 30%, B. 40%, C. 20%, D. 50%.
C: 20%
Answer: C: 20% 
Explanation: Ans: C (20%) Ref: Klingensmith ME, Chen LE, Glasgow SC, Goers T4. Melby SJ, Reticular Formation, EEC and sleep. In: Washington Manual of Surgery. 5th Edn, Lippincott Williams & Wilkins 2008; 7: 145Explanation: (See the following table)