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: Pediatrics
True regarding galactosemia 
Select and explain. 
A. Mental retardation occurs, B. Defect in epimerase, C. Defect in galactose 1PO4 uridyl transferase, D. All the above
D: All the above
Answer: D: All the above 
Explanation: Inability to metabolise galactose occurs in galactosemia which may be caused by deficiency of galactose-1-phosphate uridyl transferase,UDP-Galactose-4-Epirnerase and galactokinase.
Out of three, most common is Galactose =1-phosphate uridyl transferase deficiency.