Which of the following cofactors is required for decarboxylation of alpha-ketoacids?

Vitamin B1, or thiamine, is the coenzyme required (as the pyrophosphate) for the decarboxylation of alpha-ketoacids. An example of this reaction is pyruvate decarboxylase reaction in alcoholic fermentation. Other reactions such as that catalyzed by pyruvate dehydrogenase also rely on thiamine pyrophosphate for decarboxylation, but require other cofactors as well. Thiamine is also required for the generation of pentose phosphates for nucleotide synthesis in the pentose phosphate pathway (hexose monophosphate shunt), serving as a cofactor for transketolase. Vitamin B2, or riboflavin, is a constituent of FMN (flavin mononucleotide) and FAD (flavin adenine dinucleotide). It functions in hydrogen and electron transpo. Vitamin B3, or niacin (nicotinic acid), is a coenzyme that is also involved in hydrogen and electron transpo. Nicotinic acid functions in the form of NAD and NADP. Vitamin B5, or pantothenic acid, is conjugated with coenzyme A to act as a carboxylic acid carrier. Ref: Ender D.A. (2011). Chapter 44. Micronutrients: Vitamins & Minerals. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds),Harper's Illustrated Biochemistry, 29e.