Question

Artificial selection was used on corn to produce a single strain of corn with increased growth rates and greater resistance to a fungus. Although farmers have continued to select for these traits, the productivity of this strain is no longer increasing. This suggests that:_____________.

Answer 1

The natural variation for these traits has been eliminated

Step-by-step explanation:

Natural variation occurs when there's a variation in the genetic and epigenetic material of a population (corn), in this case, caused by artificial selection. Since this variation is not happening anymore, this means that the genetic material is not being transmitted any longer and therefore the natural variation has been eliminated.

I hope you find this information useful and interetsing! Good luck!