The correct answer is option 2: glucose. Glucose is the main type of sugar found in the human bloodstream. It is a simple sugar or monosaccharide that is produced through the breakdown of carbohydrates in our diet. It serves as the primary source of energy for our bodies and is transported through the bloodstream to reach our cells. Other types of sugar, such as sucrose and fructose, are more commonly found in foods and are broken down into glucose during digestion. Lactose, on the other hand, is a sugar found in dairy products and is made up of glucose and galactose. Therefore, option 2, glucose, accurately represents the large amount of sugar present in human blood.