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 of the following vitamins serves as a cofactor in carboxylation reactions? 
Select and explain. 
A. Thiamine, B. Riboflavin, C. Biotin, D. Pantothenic acid
C: Biotin
Answer: C: Biotin 
Explanation: Reference: Harpers illustrated biochemistry 30th edition