This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteria, Subject name: Microbiology
A seven year old boy presented to the emergency department with high grade fever on the previous day. He complained of headache, was disoriented and had projectile vomiting. On examination, the neck rigidity was seen and kernig's sign was positive. A lumbar puncture was carried out for Gram staining, Culture, complete blood counts and serum biochemistry. Gram staining of CSF showing gram negative cocci, what would be the possible cause of infection? 
Select and explain. 
A. E. coli, B. Meningococcus, C. Hemophilus, D. Pneumococcus
B: Meningococcus
Answer: B: Meningococcus 
Explanation: Ans. is 'b' i.e., MeningococcusImage description - It is Gram stain of CSF showing Gram negative oval cocci, arranged typically in pairs, with the adjacent sides flattened. The intracellular presence of Meningococci inside the polymorphs in CSF sample is characteristic finding.