**Core Concept**
Cerebral angiography is a medical imaging technique used to visualize the blood vessels in the brain. The procedure involves injecting a contrast agent, or dye, into the blood vessels to create detailed images of their structure and function.

**Why the Correct Answer is Right**
The correct answer is the internal carotid artery (ICA), which is typically the first vessel injected in cerebral angiography. This is because the ICA is a major artery that supplies blood to the brain and is often the site of pathology such as aneurysms or stenosis. The dye is injected into the ICA to visualize the blood vessels in the anterior cerebral circulation, including the anterior cerebral artery, middle cerebral artery, and posterior communicating artery.

**Why Each Wrong Option is Incorrect**
**Option A:** The external carotid artery is not typically injected in cerebral angiography, as it supplies blood to the face and neck rather than the brain.
**Option B:** The vertebral artery is not typically injected in cerebral angiography, as it supplies blood to the posterior circulation of the brain rather than the anterior circulation.
**Option C:** The basilar artery is not typically injected in cerebral angiography, as it is a terminal artery that arises from the fusion of the two vertebral arteries, and injecting dye here would not provide adequate visualization of the entire cerebral circulation.

**Clinical Pearl / High-Yield Fact**
In cerebral angiography, the internal carotid artery is typically the first vessel injected, and the procedure is usually performed under fluoroscopic guidance to ensure accurate placement of the catheter.

**Correct Answer:** C. Internal carotid artery.