Fumarase, an enzyme in the Krebs cycle which catalyzes the conversion of fumarate to malate, belongs to
Lyase
Ligase
Isomerase
Dehydrogenase
Fumarase is an enzyme that in the Krebs cycle acts as a catalyst for the reaction of water and fumarate to form L-malate. It is lyase enzyme that catalyze reactions involving either the cleavage or formation of chemical bonds.
Hence, the correct option is (a).