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
All of the following are vitamers of Vitamin B6, except: 
Select and explain. 
A. Pyridoxine, B. Pyridoxone, C. Pyridoxal, D. Pyridoxamine
B: Pyridoxone
Answer: B: Pyridoxone 
Explanation: Vitamers:
The term vitamers represents the chemically similar substances that possess qualitatively similar vitamin activity. 
Some good examples of vitamers are given below:

Retinol, retinal and retinoic acid are vitamers of vitamin A.
Pyridoxine, pyridoxal and pyridoxamine are vitamers of vitamin B6.

Key Concept:
Pyridoxine, pyridoxal and pyridoxamine are vitamers of vitamin B6.
Ref : 1- Textbook of Biochemistry, Satyanarayana