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: Surgery
How much loss of circulating body fluid is within normal compensatory mechanism of body 
Select and explain. 
A. 15% loss, B. 20% loss, C. 30% loss, D. 40% loss
D: 40% loss
Answer: D: 40% loss 
Explanation: Further loss of circulating volume overloads the body’s compensatory mechanisms and there is progressive renal, respiratory and cardiovascular decompensation. In general, loss of around 15% of the circulating blood volume is within normal compensatory mechanisms. Blood pressure is usually well maintained and only falls after 30–40% of the circulating volume has been lost.