A6-month-old infant presents to the clinic with failure to thrive, a history of frequent respiratory infections, and increasing exhaustion during feedings. on physical examination, a systolic murmur is detected, no central cyanosis, and chest radiography reveals cardiomegaly. an echocardiogram is done that shows left-to-right shunting. this assessment data is characteristic of what? a. tetralogy of fallotb. coarctation of the aortac. pulmonary stenosisd. ventricular septal defect