This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Physiology
[{'content': 'Increase blood flow to lungs cause \nSelect and explain. \nA. No change in pulmonary vascular resistance, B. Increased pulmonary vascular resistance, C. Decreases pulmonary vascular resistance, D. Initial increase followed by decrease in pulmonary vascular resistance', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Other causes include obstructive sleep apnea, congenital hea disease, chronic hypoxemia, pulmonary thrombosis (blood clots), or left ventricular failure. ... Hemodynamically, PAH can be caused by increased right ventricular output, increased pulmonary systemic vascular resistance, or increased pulmonary venous pressure Ref: guyton and hall textbook of medical physiology 12 edition page number:311,312,313', 'role': 'assistant'}]