Question

a polysaccharide is a type of polymer. polymers are molecules made of many—often hundreds or thousands—of repeating units called monomers. in polysaccharides, the monomers are simple sugars like glucose, fructose, or galactose. some polysaccharides have only one type of monomer, while other polysaccharides have two or more different types of monomers. select the polysaccharide.

Explanation:

A polysaccharide is a polymer made of many repeating sugar monomers. The first structure has two different sugar units (so not a polysaccharide with repeating same or few types? Wait, no—wait, polysaccharides can have one or more, but the key is being a polymer (many monomers). The second is a single sugar (monosaccharide). The third has many repeating similar sugar units (monomers), so it's a polymer (polysaccharide) as it consists of multiple (many) repeating sugar monomers.

Answer:

The third structure (the one with multiple repeating sugar - like units connected in a chain) is the polysaccharide.