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: Medicine
Cheilosis may result from deficiency of all except : 
Select and explain. 
A. Vitamin B12, B. Iron, C. Nicotinic acid, D. Riboflavin
A: Vitamin B12
Answer: A: Vitamin B12 
Explanation: None