Answer: The correct answer for the fill in the blank is C) Polysaccharides.
Complex sugars are called polysaccharides, which are formed when more than two simple sugar are linked together. The simple sugars are linked by glycosidic bond.
Example- Glycogen is a storage polysaccharide, which is formed by the repeating units of glucose ( simple sugar).
On the contrary, monosaccharides ( single sugar like glucose) and disaccharides ( two sugars like lactose) are simple sugar as they are made up of one and two units of sugar respectively.
Thus, the correct answer is C) Polysaccharide.