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: Physiology
Following constitute dietary fibres except : 
Select and explain. 
A. Pectin, B. Cellulose, C. Hemicellulose, D. Riboflavin
D: Riboflavin
Answer: D: Riboflavin 
Explanation: D i.e. Riboflavin