This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hypeension, Subject name: Medicine
All are causes of pulmonary hypeension, except? 
Select and explain. 
A. Hyperventilation, B. Morbid obesity, C. High altitude, D. Fenfluramine
A: Hyperventilation
Answer: A: Hyperventilation 
Explanation: Hypoxia leads to constriction of pulmonary aery and development of pulmonary aery hypeension. Morbid obesity leads to obstructive sleep apnea and can lead to PAH High altitude will also lead to hypoxia and development of PAH. A causal relationship has been established between exposure to several anorexigens, including aminorex and the fenfluramine, and the development of PAH.