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
Eye drops of which sulphonamide is used clinically ? 
Select and explain. 
A. Sulfacetamide, B. Sulfamethoxazole, C. Sulfinpyrazone, D. All
A: Sulfacetamide
Answer: A: Sulfacetamide 
Explanation: None