I believe the polysaccharide that provides rigidity and strength in plants would be cellulose. As this is one of the essential components found in the cell wall of plant cells.
Death by a predator is more natural because it follows the rules of the food chain and keeps nature in balance, keeping the environment healthy. However, whenever an animal dies of starvation, it means the food chain is out of balance since the animal wasn't in an environment where it could find something to feed off of.
You can use refraction which is the bending of light through a transparent material. Also the freezing and boiling points of water. One last one is the Cartesian five experiment, this shows the density of water. Hope this helped.
The answer is A.the site on an enzyme where the substrate binds
