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: Medicine
[{'content': 'A 21-year old male presents with exertional dyspnea, raised JVP and loud P2. ECG shows right axis deviation. All of the following conditions are possible except : \nSelect and explain. \nA. Atrial septal defect, B. Mitral stenosis, C. Ostium primum, D. Pulmonary thromboembolism', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]