Auscultation of a 3 year-old child's heart reveals a pansystolic, harsh murmur. It is heard loudest over the lower left sternal border. This finding is consistent with a:

Rationale: A. A pericardial friction rub is a scratching or grating sound caused by inflammation of the pericardium and is not typically described as a pansystolic murmur. B. A venous hum is a continuous, low-pitched sound heard over the neck and upper chest, not a harsh pansystolic murmur at the lower left sternal border. C. A patent ductus arteriosus usually produces a continuous “machinery-like” murmur rather than a pansystolic murmur. D. A ventricular septal defect (VSD) often presents as a pansystolic, harsh murmur best heard at the lower left sternal border. The intensity of the murmur may vary with the size of the defect, but this location and quality are classic for VSD in a young child.