The enzymes catalase and malate dehydrogenase are both classified as oxidoreductases. Catalase has a heme group present at its catalytic site, whereas malate dehydrogenase has no bound cofactors or prosthetic groups and uses NAD as a coenzyme. What can you infer about these two enzymes

one uses metal ion catalysis, while the other uses a nonmetal group to transfer electrons

Explanation:

A prosthetic group is a non-peptide (non-protein) component of a conjugated protein, which is covalently linked to the protein and is required for its activity. A heme group is a prosthetic group composed of a protoporphyrin ring and an iron atom in the center. Catalase is a tetramer composed of 4 heme groups which allow the enzyme to react with hydrogen peroxide (H2O2) in order to catalyze its decomposition to water (H2O) and oxygen (O2). Moreover, a cofactor is a non-protein compound and/or metallic ion that is required by an enzyme for its activity. Nicotinamide adenine dinucleotide (NAD) is a coenzyme involved in oxidation-reduction chemical reactions by carrying electrons from one reaction to another. NAD exists in two different states: an oxidized state (NAD+) and a reduced state (NADH, H for hydrogen).

the answer will be a) proteins i believe