**Core Concept**
Munson's sign is a clinical feature that indicates a palpable and visible indentation at the lower border of the left lobe of the liver, which is a sign of spleen enlargement (splenomegaly). This sign is named after the American physician and surgeon Charles Munson, who first described it.

**Why the Correct Answer is Right**
Munson's sign is observed when the spleen is enlarged and presses against the left lobe of the liver, causing a visible and palpable indentation on the liver's surface. This occurs due to the spleen's increased size and its proximity to the liver. The liver's left lobe is more susceptible to this indentation due to its anatomical position.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Munson's sign is not associated with liver pathology such as cirrhosis or liver cancer. While liver conditions can cause spleen enlargement, Munson's sign specifically indicates a direct effect of the spleen on the liver.
**Option B:** This option is incorrect because the Kehr's sign is a different clinical feature that indicates pain referred to the left shoulder due to spleen rupture or hemorrhage. It is not related to liver or spleen enlargement.
**Option C:** This option is incorrect because the Courvoisier's law is a clinical sign associated with obstructive jaundice, which is not directly related to Munson's sign.

**Clinical Pearl / High-Yield Fact**
Munson's sign is an important clinical feature to recognize, as it can indicate underlying conditions such as portal hypertension, infections, or malignancies that cause spleen enlargement.

**Correct Answer:** D. Spleen enlargement (splenomegaly)