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
Muscle glycogen, which cannot contribute to blood glucose due to the absence of which enzyme? 
Select and explain. 
A. Phosphoglutamase, B. Branching enzyme, C. Debranching enzyme, D. Glucose-6-phosphotase
D: Glucose-6-phosphotase
Answer: D: Glucose-6-phosphotase 
Explanation: None