This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Pharmacology
A 14 year old boy present with headache, fever and cought for 2 days. Sputum is scant and non-purulent and gram stain reveals many whit cells but no organisms. The treatment should be initiated with: 
Select and explain. 
A. Cefazolin, B. Erythromycin, C. Amikacin, D. Trovafloxacin
B: Erythromycin
Answer: B: Erythromycin 
Explanation: (Ref: KDT 6/e p729) Diagnosis is atypical pneumonia and DOC is erythromycin.