This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Biochemistry
Low insulin/glucagon levels to increase in the activity of 
Select and explain. 
A. Hexokinase, B. Glucokinase, C. Glucose-6-phosphatase, D. Pyruvate kinase
C: Glucose-6-phosphatase
Answer: C: Glucose-6-phosphatase 
Explanation: Insulin has several effects in liver which stimulate glycogen synthesis. First, it activates the enzyme hexokinase, which phosphorylates glucose, trapping it within the cell. Coincidently, insulin acts to inhibit the activity of glucose-6-phosphatase.When the insulin level is decreased, activity of enzyme glucose-6-phosphatase is increased, thereby increasing glycogenolysis and gluconeogenesis