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: Unknown
Carboxylation is governed by - 
Select and explain. 
A. Biotin, B. Niacin, C. Thiamine, D. Pyridoxine
A: Biotin
Answer: A: Biotin 
Explanation: Ans. is 'a' i.e., Biotin VitaminActive form (coenzvmes)Reaction typeB1 (Thiamin)Thiamine pyrophosphate (TPP)Oxidative decarboxylation, TransketolationB2 (Riboflavin)FMNt FADOxidation / Reduction (Redox reaction)B3 (Niacin)NAD\ NADP"Oxidation / Reduction (Redox reaction)B6 (Pyridoxin)Pyridoxal phosphate (PLP)Transamination, deamination, decarboxylation, condensation, trans-sulfurationBp (cobolamin)Methylcobalamin, deoxyadenosylcobalaminIsomerization of methylmelonyl-CoA to succinvl-CoA, synthesis of methionine from homocysteineFolic acidTetrahydrofolate (THF)One carbon group transferBiotinBiocytinCarboxylationPantothenic acidPentothenate in CoA and ACPAcyl group transferVitamin KVitamin KCarboxylation of glutamic acid residue