Lactose is made up of:

Lactose is a disaccharide made up of one molecule of glucose and one molecule of galactose, joined by a β-1,4 glycosidic bond. It is the primary sugar found in milk and dairy products, commonly known as 'milk sugar.' Lactose is hydrolyzed into glucose and galactose by the enzyme lactase in the small intestine. People deficient in lactase suffer from lactose intolerance. Sucrose (table sugar) is made of glucose and fructose, while maltose is made of two glucose molecules. Therefore, the correct composition of lactose is glucose and galactose.