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
Stagnant hypoxia is seen in ? 
Select and explain. 
A. COPD, B. Anemia, C. CO poisoning, D. Shock
D: Shock
Answer: D: Shock 
Explanation: Ans. is 'd' i.e., Shock