**Core Concept**
In a ventricular septal defect (VSD), blood flows from the left ventricle to the right ventricle due to the pressure gradient between the two chambers. This results in a left-to-right shunt, where oxygenated blood from the left ventricle mixes with deoxygenated blood in the right ventricle. The increased volume load on the right heart leads to signs of pulmonary hypertension and right heart enlargement.

**Why the Correct Answer is Right**
The characteristic murmur of VSD is pansystolic, meaning it starts at the beginning of systole and continues throughout. This occurs because the blood flow through the defect is continuous throughout systole. The murmur is typically best heard at the left lower sternal border. Left atrial hypertrophy can occur in VSD due to the increased volume load on the left heart, which can lead to left atrial enlargement.

**Why Each Wrong Option is Incorrect**
**Option A:** Left to right shunt is a characteristic of VSD, as blood flows from the left ventricle to the right ventricle. This is not incorrect.

**Option B:** Pansystolic murmur is a characteristic of VSD, as it is the result of the continuous blood flow through the defect. This is not incorrect.

**Option D:** Left atrial hypertrophy can occur in VSD due to the increased volume load on the left heart. This is not incorrect.

**Clinical Pearl / High-Yield Fact**
A classic exam trap in VSD is to remember that the murmur is typically pansystolic, and the left atrial enlargement can lead to left atrial hypertrophy. Additionally, the presence of a VSD can lead to signs of pulmonary hypertension, such as an increased pulmonary artery pressure and right heart enlargement.

**Correct Answer Line**
✓ Correct Answer: C. Reverse splitting of S2