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: Medicine
Carotid body receptors are stimulated when there is: 
Select and explain. 
A. Increased O2 tension, B. Decreased O2 tension, C. Decreased CO2, D. Increased heart rate
B: Decreased O2 tension
Answer: B: Decreased O2 tension 
Explanation: None