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: Ophthalmology
Which one among the following is not used in opthalmia neonatorum? 
Select and explain. 
A. Erythromycin, B. Bacitracin eye ointment, C. Gentamycin, D. Local penicillin
D: Local penicillin
Answer: D: Local penicillin 
Explanation: The most common etiologies of ophthalmia neonatorum are chemical conjunctivitis (hyperemia and mucoid discharge during the first 24 hours postpaum) caused by silver nitrate or erythromycin prophylaxis, herpes simplex, Neisseria gonorrhoeae and N. meningitidis, and Chlamydia trachomatis. Systemic treatment of erythromycin, gentamycin and bacitracin are used for the treatment. Topical treatment is not effective. Please note that local preparations of penicillin is barred in India.