**Core Concept**
Aortic regurgitation (AR) is characterized by backward flow of blood from the aorta into the left ventricle during diastole. This results in a characteristic diastolic murmur, typically described as a high-pitched, decrescendo, blowing murmur heard best at the left sternal border. The murmur arises due to turbulent flow during early diastole when the aortic valve fails to close properly.

**Why the Correct Answer is Right**
In aortic regurgitation, the hallmark murmur is a **high-pitched, decrescendo, diastolic murmur** (Option A), due to backward flow during diastole. Option B describes a **soft, low-pitched mid-diastolic rumbling murmur**, which is more consistent with mitral regurgitation or mitral stenosis. Option C, a **mid-systolic ejection murmur**, may be present due to turbulent flow during systole, especially in severe AR. However, a **pansystolic murmur** (Option D) is not associated with aortic regurgitation. Pansystolic murmurs are typically seen in conditions like ventricular septal defect or severe valvular regurgitation involving multiple valves, not isolated aortic regurgitation.

**Why Each Wrong Option is Incorrect**
Option A: This is the classic murmur of aortic regurgitation, not a false positive.
Option B: Though less common, a mid-diastolic rumbling murmur can be a clue to mitral regurgitation, but in AR, it is not typical. However, it may be misinterpreted as part of the spectrum, so it's not the best choice to exclude.
Option C: A mid-systolic ejection murmur can occur due to turbulent flow in severe AR, especially with ventricular volume overload.

**Clinical Pearl / High-Yield Fact**
Always remember: **Aortic regurgitation = high-pitched, decrescendo, diastolic murmur**. A pansystolic murmur suggests a ventricular septal defect or severe combined valvular disease, not isolated aortic regurgitation.

✓ Correct Answer: D. Pansystolic murmur