Which of the following is not a monosaccharide

Lactose is not a monosaccharide but a disaccharide. It is made of two simple sugars glucose and galactose. Monosaccharides such as glucose fructose and glyceraldehyde are the basic building blocks of carbohydrates. They are simple sugars that provide quick energy to the body. Lactose is found in milk and requires the enzyme lactase for digestion. People who lack lactase are lactose intolerant and experience digestive problems when consuming dairy. This question tests basic knowledge of biochemistry and nutrition. The correct answer is option A lactose since it is a disaccharide not a monosaccharide.