Meningitis in children 1 mo soap 2

A 2-year-old unvaccinated child presents with a high fever, irritability, and a bulging fontanelle. Which organism is the most likely cause of bacterial meningitis in this patient?

1: Neisseria meningitidis
2: Streptococcus pneumoniae
3: Haemophilus influenzae type B
4: Listeria monocytogenes