Which natural sugar is primarily found in milk?

Lactose is the natural sugar primarily found in milk, making it the correct answer. It is a disaccharide composed of two simpler sugars, glucose and galactose. Lactose is unique to dairy products and is the sugar that provides energy and sweetness to milk. When consumed, it is broken down by the enzyme lactase in the human body, allowing for the absorption of its component monosaccharides.

Fructose is primarily found in fruits and honey, while sucrose, commonly known as table sugar, is a disaccharide found in a variety of plants but is not the main sugar in milk. Glucose is a monosaccharide that is present in various foods, including fruits and vegetables, but it is not the primary sugar in milk. This distinction emphasizes the specific role of lactose as a key source of carbohydrates in dairy products.