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
True about Niacin is 
Select and explain. 
A. Oral manifestation of its deficiency is Raw beefy tongue, B. 60 mg of tryptophan is equivalent to 1 mg of Niacin, C. Deficiency cause pellagra, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: None