**Core Concept**
Haematogenous spread to the brain occurs through the bloodstream, where pathogens or infected cells are carried from a primary site of infection to the central nervous system (CNS). This type of spread can lead to various forms of brain infections, including abscesses, meningitis, and encephalitis.

**Why the Correct Answer is Right**
Haematogenous spread to the brain is a common mechanism for infections such as tuberculous meningitis, where Mycobacterium tuberculosis is carried from the lungs to the CNS via the bloodstream. Similarly, fungal infections like cryptococcal meningitis can spread through haematogenous routes, with Cryptococcus neoformans entering the brain from the lungs or skin. Another example is bacterial infections like Listeria monocytogenes, which can invade the brain via the bloodstream, particularly in immunocompromised individuals.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided, so we cannot evaluate its correctness.
**Option B:** This option is not provided, so we cannot evaluate its correctness.
**Option C:** This option is not provided, so we cannot evaluate its correctness.
**Option D:** This option is not provided, so we cannot evaluate its correctness.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that haematogenous spread to the brain can occur in immunocompromised patients, those with certain underlying medical conditions, or in cases of severe infection. Recognizing the potential for CNS involvement in systemic infections is crucial for prompt diagnosis and treatment.

**Correct Answer:** D.