Final answer:
Lactose is a disaccharide composed of glucose and galactose linked by a glycosidic bond. It's one of the primary disaccharides found in the human diet and is broken down during digestion into its monosaccharide components.
Step-by-step explanation:
Lactose is a disaccharide formed by the formation of a glycosidic bond between glucose and galactose. This bond is a β-1,4-glycosidic linkage, which is a type of covalent bond that joins a carbohydrate (sugar) molecule to another group, which can also be a carbohydrate. Lactose, commonly known as milk sugar, is one of the three major disaccharides important in the human diet, with the others being sucrose and maltose.
During digestion, disaccharides like lactose are hydrolyzed into their component monosaccharides by enzymes in the small intestine. Lactose is broken down into glucose and galactose, which are then absorbed into the bloodstream and transported to the cells for energy or other metabolic processes. The correct answer to the question is therefore b) a glycosidic bond between glucose and galactose.