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: Pathology
Magenta tongue is found in 
Select and explain. 
A. Riboflavin deficiency, B. Scarlet fever, C. Familial dysautonomia, D. Median rhomboid glossitis
A: Riboflavin deficiency
Answer: A: Riboflavin deficiency 
Explanation: None