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
The first physiological response to high environmental temperature is: 
Select and explain. 
A. Sweating, B. Vasodilatation, C. Decrease heat production, D. Non-shivering thermogenesis
B: Vasodilatation
Answer: B: Vasodilatation 
Explanation: None