This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Medicine
The majority of cases of community acquired pneumomia are due to infection with- 
Select and explain. 
A. Legionella pneumophila, B. Streptococcus pneumoniae, C. Haemophilus influenzae, D. Staphylococcus aureus
B: Streptococcus pneumoniae
Answer: B: Streptococcus pneumoniae 
Explanation: The most common infective agent of community acquired pneumonia is Streptococcus pneumoniae.Most cases are spread by droplet infection.Viral infections are impoant causes of CAP in children. Reference:Davidson's Medicine-22nd edition,page no:682