This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory, Subject name: Medicine
Which is a feature of high altitude pulmonary edema 
Select and explain. 
A. Associated with low cardiac output, B. Associated with pulmonary hypertension, C. Occurs only in unacclamatized persons, D. Exercise has no effect
B: Associated with pulmonary hypertension
Answer: B: Associated with pulmonary hypertension 
Explanation: Ans. is 'b' i.e. associated with pulmonary hypertension [Ref: Harrison 17/e, p 1707 (16/e, p 1617); ACP Medicine ' (2006); Ganong 22/e, p 685; www.emedicine.com/MED/topicl956.htmJHigh altitude pulmonary edema (HAPE) is a life-threatening form of non-cardiogenic pulmonary edema that occurs in otherwise healthy mountaineers at altitudes above 2,500 meters (8,200 feet).HAPE belongs to a spectrum of High altitude illness. HAPE and High Altitude Cerebral Edema are most ominous forms of High altitude illness. Milder forms are - acute mountain sickness, retinal hemorrhages, and peripheral edema.The initial insult that causes HAPE is excessive hypoxia caused by the lower air pressure at high altitudes. The mechanisms by which this shortage of oxygen causes HAPE are poorly understood, but two processes are believed to be important:Increased pulmonary arterial and capillary pressures (pulmonary hypertension) secondary to hypoxic pulmonary vasoconstrictionAn idiopathic non-inflammatory increase in the permeability of the vascular endothelium.* Treatment includesDescent from altitude,BedrestOxygen " Inhaled nitric oxideNifedipine.