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: Pathology
Lobar pneumonia is caused predominantly by: 
Select and explain. 
A. Klebsiella pneumoniae, B. Staphylococcus pyogenes, C. Haemophilus influenzae, D. Streptococcus pneumoniae
D: Streptococcus pneumoniae
Answer: D: Streptococcus pneumoniae 
Explanation: Most cases of lobar pneumonia are caused by S. pneumoniae (reclassification of the pneumococcus). Streptococcal or pneumococcal pneumonia involves one or more lobes and is often seen in alcoholics or debilitated persons.