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
One of the following is due to point mutation- 
Select and explain. 
A. Colour blindness, B. Sickle cell anemia, C. Diabetes, D. Pophyria
B: Sickle cell anemia
Answer: B: Sickle cell anemia 
Explanation: Ans. is 'b' i.e., Sickle cell anemia