An 8-year-old boy presents fever， headache and cough for 6 days. Chest X-ray shows cloudy infiltration. Mycoplasma antibody(MP-IgM) is 1 : 320. The diagnosis is
A
acute bronchitis
B
staphylococci aureus pneumonia
C
adenovirus pneumonia
D
respiratory syncytial virus pneumonia
E
mycoplasma pneumonial pneumonia