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
Tetracycline ointment for mass prophylaxis: 
Select and explain. 
A. 0.10%, B. 0.50%, C. 1%, D. 5%
A: 0.10%
Answer: A: 0.10% 
Explanation: Ans. 0.1%