Answer:
Because they don't have fertilizer.
Explanation:
Well, if this was a long time ago, then farmers did not have fertilizer. So, there are bacteria on the roots of plants that convert nitrogen into a usable form. It's very important for growing, and when farmers harvest the crop, not much of the nitrogen is returned to the land, so it is not as fertile. Fertilizer is largely consisted of nitrogen, so that is why farmers use fertilizers today. But "a long time ago," farmers did not have fertilizer.
Answer:
<u><em>The correct option is C) genetic variation</em></u>
Explanation:
Genetic variation can be described as the differences present in the genetic material i.e DNA of organisms present in a population. Genetic diversity allows organisms of a species to better adapt to an environment. A population in which the genetic variability is scarce might become wiped out by a disease or an invading predator.
As the birds show different variations hence the term that best described them is genetic variation.
