A patient presents with sore throat, swollen tongue, and dry cracked lips. Which B vitamin deficiency is most consistent with these signs and what is the coenzyme it helps form?

• A. Niacin (B3) deficiency, which primarily disrupts CoA formation leading to cracked lips.
• B. Pantothenic acid (B5) deficiency, which prevents NAD+ formation and causes mucosal lesions.
• C. Thiamine (B1) deficiency, which lowers biotin-dependent coenzymes producing oral mucosal changes.
• D. Riboflavin (B2) deficiency, which is required to form FAD (flavin adenine dinucleotide).

Answer: (D)