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
One of the following is earliest indication ofconcealed acute bleeding - 
Select and explain. 
A. Tachycardia, B. Postural HT, C. Oliguria, D. Cold clammy fingers
A: Tachycardia
Answer: A: Tachycardia 
Explanation: None