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 comes with history of unresponsive fever and cough. X-ray revealed pneumonia. Sputum examination showed gram positive, paially acid fast bacteria with branching filaments that grows on sheep blood agar. The most likely etiologic agents is: 
Select and explain. 
A. Actinomycetes, B. Nocardia, C. Aspergillosis, D. Pneumococci
B: Nocardia
Answer: B: Nocardia 
Explanation: Ans. (b) i.e. Nocardia