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: Pharmacology
A 14-year-old boy present with headache, fever, and cough for 2 days. Sputum is scant and non-purulent and gram stain reveals many white 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: None