This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Intestinal Infections, Worm Infestations, Subject name: Social & Preventive Medicine
Drug of choice for Prophylaxis against Diphtheria is 
Select and explain. 
A. Ciprofloxacin, B. Amoxycillin, C. Erythromycin, D. Cotrimoxazole
C: Erythromycin
Answer: C: Erythromycin 
Explanation: Control of Diphtheria Prophylaxis of Diphtheria Erythromycin Non-immunized contacts Prophylactic Penicillin/Erythromycin + 1000-2000 units antitoxin + active immunization DOC for carriers Erythromycin DOC for cases Penicillin/Erythromycin (given along with anti-toxin)