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
Which of the following always indicates obstruction to the airway? 
Select and explain. 
A. Slow pounding pulse, B. Strenuous breathing, C. Increase in pulse rate, D. Decrease in blood pressure
B: Strenuous breathing
Answer: B: Strenuous breathing 
Explanation: None