**Core Concept**
Bile duct obstruction leads to a cascade of pathological changes in the liver and bile ducts, characterized by the accumulation of bile and its components. This results in damage to the bile duct epithelium and surrounding liver tissue.

**Why the Correct Answer is Right**
Bile duct obstruction causes cholestasis, which leads to the accumulation of bile acids, bilirubin, and other bile components. This results in the activation of stellate cells, leading to fibrosis and the formation of bile duct strictures. The histopathologic features of bile duct obstruction include bile duct dilation, fibrosis, and the presence of bile duct epithelial cells with nuclear enlargement, pleomorphism, and hyperchromasia. The bile duct epithelium may also exhibit squamous metaplasia, and there may be an increase in the number of eosinophils and lymphocytes.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the histopathologic features of bile duct obstruction.

**Option B:** This option is incorrect because it does not mention the key histopathologic features of bile duct obstruction, such as bile duct dilation and fibrosis.

**Option C:** This option is incorrect because it is too broad and does not specifically describe the histopathologic features of bile duct obstruction.

**Clinical Pearl / High-Yield Fact**
One key histopathologic feature of bile duct obstruction is the presence of bile duct epithelial cells with nuclear enlargement, pleomorphism, and hyperchromasia, which can be used to distinguish it from other liver lesions.

**Correct Answer: D. Bile duct dilation, fibrosis, and bile duct epithelial cell changes.**