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: Biochemistry
The MOST common enzyme deficiency responsible for Galactosemia is related to which of the following enzymes? 
Select and explain. 
A. UDP galactose epimerase, B. Galactokinase, C. Galactosidase, D. Galactose-l-phosphate uridyl transferase
D: Galactose-l-phosphate uridyl transferase
Answer: D: Galactose-l-phosphate uridyl transferase 
Explanation: Galactose-1-phosphate uridyltransferase (GALT) deficiency is the most common enzyme deficiency that causes hypergalactosemia. Hereditary galactosemia is among the most common carbohydrate metabolism disorders and can be a life-threatening illness during the newborn period. Ref: Liver Disease in Children By Frederick J. Suchy, Ronald J. Sokol, William F. Balistreri, 2007, Page 596; Textbook of Biochemistry and Human Biology by L. M. Srivastava, Page 353; Saunders manual of pediatric practice by Laurence Finberg, Ronald E. Kleinman, Page 238