question: Q:A 2-year-old boy is presented to the pediatrician due to poor weight gain and easy fatigability. His mother states that the patient barely engages in any physical activity as he becomes short of breath easily. The prenatal and birth histories are insignificant. Past medical history includes a few episodes of upper respiratory tract infection that were treated successfully. The patient is in the 10th percentile for weight and 40th percentile for height. The vital signs include: heart rate 122/min and respirations 32/min. Cardiac auscultation reveals clear lungs and a grade 2/6 holosystolic murmur loudest at the left lower sternal border. The remainder of the physical examination is negative for clubbing, cyanosis, and peripheral edema. Which of the following is the most likely diagnosis in this patient?? 
  {'A': 'Patent ductus arteriosus (PDA)', 'B': 'Atrial septal defect (ASD)', 'C': 'Ventricular septal defect (VSD)', 'D': 'Coarctation of aorta', 'E': 'Tetralogy of Fallot (TOF)'},