Answer:
its "A" water flowing over a tall cliff
Explanation:
Natural selection can only occur because of a variety in a population. Natural selection refers to environmental factors that affect a population and causes some of the population to have more surviving offspring than others. An example is a giraffe with a longer neck will be more likely to survive and reproduce (as it can gather more food from taller trees)
i believe that the cell will expand because there is less sugar in the water. if you were to add more sugar into the water, then the cell will shrink in size because sugar and salt is the same thing if you add it in water.
I would say energy myself, and this is because energy plays a key role in all of these. With trophic levels energy is being transferred amongst the levels. Food chain's is a map of how the energy is passed along the chain. Food web is a web of how energy is transferred, and this is why I would say energy is a keyword.
