A control group of the experiment is the one in which no treatment or intervention is given. So, in your case, the pea plants in which was not subjected any of the fertilizers, will serve as a control group. This is a negative control. A positive control group is the one in which an established treatment is given, which definitely leads to the production of the desired character. So, in your case, a very good well-known fertilizer which has a positive control on the growth of the pea plant, would serve as a positive control.
The is should be C, Im not 100% sure though...
Answer:
Soil Erosion
Explanation:
Basically, tillage breaks soil up, destroying its overall structure. It encourages surface runoff and therefore soil erodes more easily. In some cases soil erosion is beneficial, but in most cases, it is not. Tillage has also been found to cause the emissions of more toxic gases such as N20.
... increase their chances of displaying this said attribute in higher incidence and frequency
