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
Vitamers represent: 
Select and explain. 
A. Chemically similar  substances that  possess qualitatively similar vitamin  activity, B. Chemically dissimilar  substances that  possess qualitatively similar vitamin  activity, C. Chemically similar  substances that  possess qualitatively less vitamin  activity, D. Chemically similar  substances that  possess qualitatively more vitamin  activity
A: Chemically similar  substances that  possess qualitatively similar vitamin  activity
Answer: A: Chemically similar  substances that  possess qualitatively similar vitamin  activity 
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.

Ref :  Textbook of Biochemistry, Satyanarayana