**Core Concept**
The question is testing knowledge of the histological features of liver lesions, specifically a type of benign vascular anomaly. Cystic blood-filled spaces in the liver, lined by endothelial cells, indicate a specific type of vascular malformation.

**Why the Correct Answer is Right**
The correct term for cystic blood-filled spaces in the liver, lined by endothelial cells, is a hemangioma. Hemangiomas are benign vascular tumors composed of blood-filled spaces lined by endothelial cells. They are the most common type of benign liver tumor and are often found incidentally on imaging studies. The endothelial cells lining the spaces in hemangiomas are of the capillary type, which helps to distinguish them from other types of vascular anomalies.

**Why Each Wrong Option is Incorrect**
**Option A:** is incorrect because it does not accurately describe a type of cystic blood-filled space in the liver. While cysts can be found in the liver, they are not typically lined by endothelial cells.
**Option B:** is incorrect because it refers to a type of liver tumor that is composed of bile ducts rather than blood-filled spaces.
**Option C:** is incorrect because it refers to a type of liver tumor that is composed of hepatocytes rather than blood-filled spaces.

**Clinical Pearl / High-Yield Fact**
Hemangiomas are often found incidentally on imaging studies and are usually asymptomatic. However, large hemangiomas can cause symptoms such as abdominal pain or discomfort.

**Correct Answer: C. Hemangioma**