Which of the following is a complex carbohydrate?

Starch is classified as a complex carbohydrate because it is made up of long chains of glucose molecules linked together. This structure allows starch to serve as a significant energy reserve in plants, and it takes longer for the body to break it down into glucose compared to simple carbohydrates. As a result, starch provides a more sustained release of energy.

In contrast, glucose, fructose, and galactose are all simple carbohydrates, consisting of single sugar molecules or monosaccharides. These sugars are quickly absorbed into the bloodstream, leading to rapid spikes in energy, which is why they are not categorized as complex carbohydrates. Complex carbohydrates like starch are important in a balanced diet as they not only provide energy but also contribute to digestive health and can help in maintaining stable blood sugar levels.