This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: vitamins, Subject name: Biochemistry
Which vitamin deficiency causes glossitis and cheilosis? 
Select and explain. 
A. Thiamin, B. Riboflavin, C. Folic acid, D. Vitamin A
B: Riboflavin
Answer: B: Riboflavin 
Explanation: Riboflavin deficiency causes glossitis and cheilosis. Riboflavin Deficiency: a.Causes: Natural deficiency of riboflavin in man is uncommon because riboflavin is synthesized by the intestinal flora. Riboflavin deficiency usually accompanies other deficiency diseases such as beriberi, pellagra and kwashiorkor. b.Manifestations: Symptoms are confined to skin and mucous membranes. i. Glossitis (Greek, glossa = tongue). ii. Magenta coloured tongueiii. Cheilosis (Greek, cheilos = lip.iv. Angular stomatitis (inflammation at the corners of mouth). v. Circumcorneal vascularization. vi. Proliferation of the bulbar conjunctival capillaries is the earliest sign of riboflavin deficiency. Reference: Vasudevan Textbook of Biochemistry pg no. 393