Which type of carbohydrate is primarily stored in plant tubers such as sweet potatoes?

The correct choice is polysaccharides because they are the main form in which carbohydrates are stored in plants, particularly in tubers like sweet potatoes. Polysaccharides are long chains of monosaccharide units linked together and can be used by plants for energy storage and structural purposes. In sweet potatoes, the primary polysaccharide is starch, which consists of many glucose units joined together. This starch can later be broken down into glucose when energy is needed.

In contrast, monosaccharides are the simplest form of carbohydrates, consisting of single sugar molecules, such as glucose or fructose, and they are usually the building blocks for more complex carbohydrates. Oligosaccharides, which consist of a few monosaccharides (typically 2-10 units), are not the main storage form in plants. Disaccharides, made up of two monosaccharide units (like sucrose), also do not serve as significant storage forms compared to polysaccharides like starch. Therefore, polysaccharides are specifically suited for energy storage in plant tubers.