This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
A female presents with symptoms and signs suggestive of meningitis. MRI reveals a ring enhancing lesion in the frontotemporal region while CSF grows Gram positive bacilli. Other findings are minimally abnormal. Which of the following organisms is the most likely etiological agent - 
Select and explain. 
A. Listeria monocytogenes, B. Hemophilus influenza, C. Pneumococcus, D. Staphylococcal aureus
A: Listeria monocytogenes
Answer: A: Listeria monocytogenes 
Explanation: None