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
Key glycolytic enzymes: 
Select and explain. 
A. Phosphofructokinase, B. Hexo kinase, C. Pyruvate kinase, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: A i.e. Phosphofructo kinase; B i.e. Hexo kinase; C i.e. Pyruvate kinase