The correct option is D Maltase is an enzyme
Enzyme: A chemical substance that is found in living systems which produce changes in other substances or metabolism reactions without being changed itself. Enzymes are simply biological catalyst. Almost all the enzymes are globular proteins.
Enzymes are very specific for a particular reaction and
for a particular substrate.
Maltase is an enzyme that catalyses the hydrolysis of maltose to glucose
Thus, option (b), (c) and (d) are correct statements regarding enzyme.