Answer: The type of molecule that supports a tree's tall structure is A. polysaccharide.
Step-by-step explanation:
Polysaccharides are macromolecules consisting of many monosaccharide units. The Oxygen- hydrogen groups that make up the monomers such as glucose can form hydrogen bonds with cellulose molecules. These hydrogen bonds formed, allows for the cellulose strands to form fibres, providing trees and other plants.
Therefore, polysaccharides are molecules that supports a tree's tall structure.