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
Which of the following diseases shows Pleiotropism 
Select and explain. 
A. Marfan syndrome, B. Sickle cell disease, C. Phenylketonuria, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Pleiotropism - A single gene mutation may have phenotypic effects.