Why Do Some Otitis Media Cases Not Respond to Antibiotic

Why do some otitis media cases not respond to antibiotic treatment?

A) About 30% of cases are caused by respiratory viruses-antibiotics do not help these cases.
B) Most cases are caused by bacteria that are resistant to commonly prescribed antibiotics.
C) Otitis media is caused by viruses that constantly undergo antigenic shift and/or antigenic drift.
D) The bacterial causative organisms mutate frequently, changing their antibiotic target sites.
E) Unless the exact causative organism is identified, it is impossible to prescribe the correct antibiotic.