**Core Concept**
Holman-Miller sign refers to the presence of a characteristic, high-pitched, musical, or "galloping" murmur that is best heard at the apex of the heart in early diastole. This sign is indicative of severe aortic regurgitation, often associated with significant left ventricular dilatation and hypertrophy.

**Why the Correct Answer is Right**
The Holman-Miller sign is a result of the increased flow of blood from the left ventricle into the left atrium during diastole due to the severe aortic regurgitation. This increased flow creates a high-velocity jet of blood that impinges on the mitral valve leaflets, producing a characteristic "galloping" or musical murmur. The murmur is often described as being loudest at the apex and radiating to the axilla.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the Holman-Miller sign is not associated with mitral stenosis, which typically presents with a mid-diastolic murmur due to the narrowing of the mitral valve orifice.
* **Option B:** This option is incorrect because the Holman-Miller sign is not associated with aortic stenosis, which typically presents with a systolic ejection murmur due to the narrowing of the aortic valve orifice.
* **Option C:** This option is incorrect because the Holman-Miller sign is not associated with tricuspid regurgitation, which typically presents with a systolic murmur due to the regurgitation of blood from the right ventricle into the right atrium.

**Clinical Pearl / High-Yield Fact**
The presence of a Holman-Miller sign is often associated with severe left ventricular dysfunction and may indicate the need for urgent medical or surgical intervention to prevent further cardiac complications.

**Correct Answer: D. Aortic regurgitation.