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
Which of the following is used to treat Paroxysmal nocturnal hemoglobinuria ? 
Select and explain. 
A. Eculizumab, B. Avelumab, C. Natalizumab, D. Sarilumab
A: Eculizumab
Answer: A: Eculizumab 
Explanation: Eculizumab is monoclonal antibody against C5 complement used in the treatment of paroxysmal nocturnal hemoglobinuria.