Right answer is (b) Deoxyadenosylcobalamin
Best explanation: The enzyme which does not function as redox reaction is Deoxyadenosylcobalamin, which has a function of isomerization and transfer of methyl groups in a reaction. Flavin adenine nucleotide, Nicotinamide adenine dinucleotide, Flavin mononucleotide and Nicotinamide adenine dinucleotide phosphate are the coenzymes which function as a redox reaction.