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 patient presents to the emergency department with history of persistent fever & cough. Radiological features are suggestive of pneumonia. Sputum examination cultures reveal aerobic branching Gram positive filaments that are partially acid fast.Which of the following is the most likely etiological agent - 
Select and explain. 
A. Actinomyces israeli, B. Nocardia asteriodes, C. Aspergillus fumigatus, D. Staphylococcus aureus
B: Nocardia asteriodes
Answer: B: Nocardia asteriodes 
Explanation: None