**Core Concept**
Hepar lobatum is a rare condition characterized by calcification of the brain, often associated with tuberculosis meningitis. It results from the deposition of calcium salts in the brain parenchyma, leading to the formation of calcified nodules that resemble lobes.

**Why the Correct Answer is Right**
The calcification in hepar lobatum is thought to be a result of the body's attempt to wall off the bacterial infection. The deposition of calcium salts is likely mediated by the inflammatory response, which leads to the activation of various enzymes and the release of calcium-binding proteins. This process ultimately results in the formation of calcified nodules that can be visualized on imaging studies.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not directly related to the pathophysiology of hepar lobatum.
**Option B:** This option is incorrect because it is a different condition altogether, characterized by calcification of the basal ganglia.
**Option C:** This option is incorrect because it is a type of cerebral vasculitis, not a condition associated with calcification.

**Clinical Pearl / High-Yield Fact**
Hepar lobatum is a classic radiological finding in patients with tuberculous meningitis, and its presence should raise suspicion for this diagnosis.

**Correct Answer: D. Tuberculous meningitis**