Metaphase is the stage in which the "crossing over" occurs.
As we know chromosomes carry genetic information. This crossing over process happens in eukaryotic cells and occurs during the mitosis phases of cell division.
Hopefully this helped.
The answer is A. i say this because when they use sunlight as energy, cabon dioxide and water are converted into organic material, they are used as cellular functions ( such as biosynthesis and respiration ). An able autotroph is able to make his own food.
Answer;
He conducted an experiment with breeding pigeons.
Explanation;
The pigeons provided the perfect animal to test his theory of selection for quite a number of reasons including its trait diversity from wing structures to color patterns to size to flight patterns. From these experiments he concluded that by natural selection of randomly occurring traits that make species better suited for survival and reproduction, evolve in the astounding diversity of organisms on Earth today.
It gets polluted from fertilizers or any spilled chemicals. And those chemicals get obsorbed into the ground. And the gravity pushes them deeper in the soil, till it reaches the underground water (or aquifer)