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
Essential Pentosuria is due to defect in? 
Select and explain. 
A. Glycolysis, B. HMP Shunt, C. TCA Cycle, D. Uronic acid pathway
D: Uronic acid pathway
Answer: D: Uronic acid pathway 
Explanation: Affected individuals excrete large amounts of L-xylulose in urine. Xylulose being a reducing sugar gives Benedict's test positive. Bial's test is positive as xylulose is a pentose Reference Harper's Illustrated Biochemistry 30th Edition Pg 205