**Core Concept**
Sturge-Weber syndrome is a rare congenital disorder characterized by a distinctive port-wine stain, typically affecting the face, and associated with neurological abnormalities and glaucoma. The syndrome is caused by a somatic mutation in the GNAQ gene, leading to the overexpression of vascular endothelial growth factor (VEGF) and subsequent angiogenesis.

**Why the Correct Answer is Right**
Sturge-Weber syndrome is classically associated with a port-wine stain, a type of vascular malformation that results from the abnormal growth of blood vessels. This is due to the overexpression of VEGF, which promotes angiogenesis and leads to the formation of cavernous hemangiomas, which are a hallmark of the syndrome. The port-wine stain is typically unilateral and affects the distribution of the trigeminal nerve, often involving the ophthalmic division (V1). Cavernous hemangiomas are found in the leptomeninges, brain, and eye, and can lead to glaucoma, seizures, and developmental delays.

**Why Each Wrong Option is Incorrect**
**Option A:** Lymphangiomas are a type of malformation of the lymphatic vessels, which are not typically associated with Sturge-Weber syndrome. Lymphangiomas are more commonly seen in the neck and axilla.
**Option B:** Cavernous hemangiomas are indeed associated with Sturge-Weber syndrome, as mentioned earlier.
**Option C:** Hemangiosarcoma is a malignant tumor of blood vessels, which is not a characteristic feature of Sturge-Weber syndrome.
**Option D:** Lymphangiomas are not associated with Sturge-Weber syndrome.

**Clinical Pearl / High-Yield Fact**
Sturge-Weber syndrome is often associated with a characteristic "tram-track" calcification on CT or MRI scans, which is due to the calcification of the leptomeningeal vessels. This is a key diagnostic feature of the syndrome.

**✓ Correct Answer: A. ab. Port wine stain and cavernous hemangioma are both associated with Sturge-Weber syndrome.**