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.
Over time, those who cannot live through the temperature differences/have undesirable qualities will die off. Overtime, those with desirable qualities are left and they will continue the population.
The answer is C, because it was done on purpose, therefore NOT naturally. Not done by nature.
<span>The oceanic crust is part of the crust that is made fully out of basaltic rock and is several times thinner than the continental crust which is made out of granitic rock. Oceanic crust underlies Earth's oceans and is produced at divergent plate boundaries which are commonly referred to as mid-ocean ridges. As it grows from infilling magma and spreads away from the ridges, it will becomes cooler, thicker, and more dense, and will eventually sink into the mantle.</span>
Earthquakes can be recognized through association of plates sliding past each other.