What are the most common pathogens causing community-acquired pneumonia?

Chlamydia trachomatis, respiratory syncytial virus, Streptococcus pneumoniae, and Mycoplasma pneumoniae are the most common pathogens in patients under 18 years old.
In adults, regardless of comorbidity and age, Streptococcus pneumoniae is the most common pathogen.
In young adults, there is a relatively high incidence of Mycoplasma pneumoniae and Chlamydia pneumoniae.
After the age of 65, the frequency of Gram-negative bacilli (GNB) and anaerobes increases.
a) I and II are correct.
b) II and III are correct.
c) III and IV are correct.
d) All statements are correct.