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
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 : 
Select and explain. 
A. Atrial septal defect, B. Mitral stenosis, C. Ostium primum, D. Pulmonary thromboembolism
C: Ostium primum
Answer: C: Ostium primum 
Explanation: None