**Core Concept**
Malignant hypertension can lead to a condition known as hypertensive encephalopathy, characterized by acute brain damage due to the severe increase in blood pressure. This condition is a medical emergency and can cause a range of symptoms including headache, confusion, and seizures.

**Why the Correct Answer is Right**
The correct answer is **C. Cerebral edema**. Cerebral edema, or brain swelling, occurs when the small blood vessels in the brain become damaged due to the high blood pressure, leading to an influx of fluid into the brain tissue. This can cause increased intracranial pressure, leading to symptoms such as headache, confusion, and seizures. The presence of bilateral papilledema, or swelling of the optic disc, is a sign of increased intracranial pressure.

**Why Each Wrong Option is Incorrect**
**Option A:** **Cerebral infarction** is incorrect because it is a condition caused by a lack of blood flow to the brain, typically due to a blockage of a blood vessel, whereas cerebral edema is caused by an excess of fluid in the brain.

**Option B:** **Hemorrhagic stroke** is incorrect because it is a condition caused by bleeding in the brain, typically due to high blood pressure, but it is not the direct result of the acute increase in blood pressure in this case.

**Option D:** **Cerebral vasculitis** is incorrect because it is a condition characterized by inflammation of the blood vessels in the brain, which is not directly related to the acute increase in blood pressure in this case.

**Clinical Pearl / High-Yield Fact**
Hypertensive encephalopathy can occur rapidly in patients with severe and uncontrolled hypertension, and it is essential to lower the blood pressure quickly to prevent further brain damage.

**Correct Answer:** C. Cerebral edema