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
The earliest sign of syncope is 
Select and explain. 
A. Pallor, B. Constriction of pupil, C. Dilation of pupil, D. Bradycardia
A: Pallor
Answer: A: Pallor 
Explanation: None