The function of beta-galactosidase is to

break down glucose

produce glucose

break down lactose

produce lactose

break down lactose

β-galactosidase is necessary for organisms as it is a principal provider in the generation of energy and a source of carbons through the breaking of lactose to galactose and glucose.

β-galactosides combine carbohydrates comprising galactose where the glycosidic linkage lies above the galactose particle. Substrates of various β-galactosidases incorporate, lactose, ganglioside GM1, lactosylceramides, and various glycoproteins.

c should be the answer