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 of the following is the drug of choice of treatment of corneal ulcers caused by filamentous fungi? 
Select and explain. 
A. Itraconazole, B. Natamycin, C. Nystatin, D. Fluconazole
B: Natamycin
Answer: B: Natamycin 
Explanation: "The drug of choice for filamentous infections is natamycin and amphotericin B (0.15%) is the drug of choice for candida". ___ Atals of clinical ophthalmology
"Polyene antifungals, natamycin (5%) and amphotericin B (0.15-0.25%) are the most commonly used drugs". ____ Ocular therapeutics
"Treatment by means of local natamycin and amphotericin B drops, and miconazole ointment, these are effective against Aspergillus and fusarium (filamentous fungi)".