The correct answer is option (4) because lyases are group of enzymes that catalyse the removal of groups from substrates by mechanisms other than hydrolysis leaving double bonds. Option (1) is incorrect because transferases are enzymes catalysing a transfer of a group G (other than hydrogen) between a pair of substrate S and S′ . Option (2) is incorrect because oxidoreductases are enzymes which catalyse oxidoreduction between two substrates S and S′. Option (3) is incorrect because dehydrogenases are also known as oxidoreductases.