The correct option is A Galactose
Monosaccharides are the simplest form of sugar and the most basic units of carbohydrates. Example: Glucose, galactose and fructose.
Disaccharides are those carbohydrates which are formed when two monosaccharides are joined together. Example: Maltose, sucrose and lactose.
MonosaccharidesDisaccharidesGlucoseMaltose - Glucose + GlucoseGalactoseLactose - Glucose + GalactoseFructoseSucrose - Glucose + Fructose