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 is the marker enzyme for Endoplasmic reticulum? 
Select and explain. 
A. ATP synthase, B. 5' nucleotidase, C. Catalase, D. Glucose-6-phosphatase
D: Glucose-6-phosphatase
Answer: D: Glucose-6-phosphatase 
Explanation: ATP synthase is marker enzyme for mitochondria.
5' nucleotidase is marker enzyme for plasma membrane.
Catalase and urate oxidase is marker enzyme for peroxidase.
Glucose-6-phosphatase is marker enzyme for Endoplasmic reticulum.