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
Von Gierke's occurs due to deficiency of 
Select and explain. 
A. Glucose-6-phosphatase, B. Liver Phosphorylase, C. Muscle phosphorylase, D. Debranching enzyme
A: Glucose-6-phosphatase
Answer: A: Glucose-6-phosphatase 
Explanation: Glucose - 6- phosphatase is deficient in Von Gierke's disease.