Choice A rationale:

Bacterial meningitis is the most common and severe type of meningitis in infants and children. The causative bacteria can include Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae type b, among others.

Choice B rationale:

Fungal meningitis is less common than bacterial meningitis and is usually associated with specific risk factors, such as immunosuppression or exposure to certain environmental fungi.

Choice C rationale:

Viral meningitis is more common than bacterial meningitis, but it is usually milder and often resolves without specific treatment. Enteroviruses are the most frequent cause of viral meningitis in infants and children.

Choice D rationale:

Parasitic meningitis is a rare form of the disease and is usually associated with specific parasites, such as the amoeba Naegleria fowleri or the parasite Trypanosoma.

Choice E rationale:

Meningitis of unknown origin refers to cases where the cause of meningitis remains unidentified after thorough investigations. It is not a specific type of meningitis but rather a descriptive term for cases with uncertain etiology.