A species is a group of organisms capable of mating and producing offspring. This is another way of saying that a species is reproductively isolated.
It's C! It changes as new evidence is found.
"A good soil structure is important to allow air and water into the soil which are vital for healthy plant growth. It will improve drainage and reduce soil erosion caused by excess surface run-off."
https://www.rolawn.co.uk/soil-structure
