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: Pathology
Intrinsic cell wall defect of RBCs is feature of ? 
Select and explain. 
A. Paroxysmal nocturnal hemoglobinuria, B. Sickle cell anemia, C. Herediatary sperocytosis, D. All of the above
A: Paroxysmal nocturnal hemoglobinuria
Answer: A: Paroxysmal nocturnal hemoglobinuria 
Explanation: Ans. is 'a' i.e., Paroxysmal nocturnal hemoglobinuria