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
Which enzyme's activity is increased in low insulin/glucagon level? 
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 suppresses glucose-6-phosphatase gene.Glucose-6-phosphatase activity is increased in low insulin/glucagon level.Glucocoicoids, glucagon, epinephrine are inducers of glucose-6-phosphatase whereas insulin is repressor.Insulin upregulates the transcription of glucokinase, phosphofructokinase, and pyruvate kinase, while glucagon downregulates their transcription.Glucose-6-phosphatase plays an impoant role in the regulation of hepatic glucose production, and insulin suppresses glucose-6-phosphatase gene.