This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nose and paranasal sinuses, Subject name: ENT
Common organisms causinh sinusitis: 
Select and explain. 
A. pseudomonas, B. Moraxella catarrhalis, C. Streptococcus pneumoniae, D. H.influenza
C: Streptococcus pneumoniae
Answer: C: Streptococcus pneumoniae 
Explanation: according to scott Brown 7/e,p 1441 M/C Organism causing sinusitis in adults is also Streptococcus pneumoniae followed by H.influenza. In childreb M/C is streptococcus pnuemonia followef by both H.influenza and moraxella catarrhalis.