This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of carbohydrate, Subject name: Biochemistry
The enzyme defect in galactosemia is 
Select and explain. 
A. Aldose reductase, B. Galactose-1-phosphate uridyltransferase, C. Galactokinase, D. Aldolase B
B: Galactose-1-phosphate uridyltransferase
Answer: B: Galactose-1-phosphate uridyltransferase 
Explanation: Inability to metabolize galactose occurs in the galactosemias, which may be caused by inherited defects of galactokinase, uridyl transferase, or 4-epimerase Though deficiency of uridyl transferase is best known.Harper 30th edition pg: 205