<s>[INST] context: Community-acquired acute pneumonia refers to lung infection in otherwise healthy individuals that is acquired from the normal environment. Streptococcus pneumonia Haemophilus influenza Staphylococcus aureus aka pneumococcus, is the most common cause of community-acquired acute pneumonia. Examination of Gram-stained sputum is an impoant step in the diagnosis of acute pneumonia The presence of numerous neutrophils containing the typical gram-positive, lancet-shaped diplococci suppos the diagnosis of pneumococcal pneumonia. It is a pleomorphic, gram-negative organism that occurs in encapsulated and nonencapsulated forms There are six serotypes of the encapsulated form (types a to f), of which type b is the most virulent. H. influenzae pneumonia, which may follow a viral respiratory infection, is a pediatric emergency and has a high moality rate It is an impoant cause of secondary bacterial pneumonia in children and healthy adults following viral respiratory illnesses. high incidence of complications, such as lung abscess and empyema [/INST] question: Most common causative organism of community-acquired acute pneumonia is: | options: A: Staphylococcus aureus B: Streptococcus pyogenes C: Streptococcus pneumoniae D: Haemophilus influenza | answer: C </s>