Question

suppose that caterpillar - resistant corn was grown in a simulation for 30 years. if the corn field and the stream look like they do in the images below at the end of year 30, which substances were used to treat the field?
herbicide only
insecticide only
herbicide and insecticide
nothing

Explanation:

The corn is caterpillar - resistant. The field looks healthy and there are no signs of herbicide or insecticide damage to the plants or the stream ecosystem. So, nothing was likely used to treat the field.

Answer:

Nothing