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: Medicine
Eculizumab an anti-C5 monoclonal antibody is used in the treatment of: 
Select and explain. 
A. NHL, B. Hodgkin's lymphoma, C. Multiple myeloma, D. Paroxysmal nocturnal hemoglobinuria
D: Paroxysmal nocturnal hemoglobinuria
Answer: D: Paroxysmal nocturnal hemoglobinuria 
Explanation: A major advance in the management of PNH has been the development of a humanized monoclonal antibody, eculizumab, directed against the complement component C5. By blocking the complement cascade downstream of C5, eculizumab abrogates complement-dependent intravascular hemolysis in all PNH patients. Reference: Harrisons Principles of Internal Medicine, 18th Edition, Pages 884-86