<prompt> A young female presents with history of dyspnea on exertion. On examination, she has wide, fixed split S2 with ejection systolic murmur IIIVI in left second intercostal space. Her ECG shows left axis deviation. The most probable diagnosis is:Total anomalous pulmonary venous drainageTricuspid atresiaOstium primum atrial septal defectVentricular septal defect with pulmonary arterial hypertension  <response>: c. Ostium primum atrial septal defectRef: Nelsons 20e p 2189, Ghai 8e p 413Wide fixed splitting of S2 in association with ejection systolic murmur suggests the diagnosis of atrial septal defectThe presence of left axis deviation in A.S.D., suggests ostium primum type of defect. 