Akey should be parallel. an example of parallel choices is

a. flower color is red;

aa. flower color is blue.

Explanation:

I imagine you are referring to a dichotomous key is a type of method used by many researchers to identify an organism. Through this kind of key, we can, for example, know the species of plant we are looking at. Just follow the key steps! It is called dichotomous because it allows two inputs. An example of parallel choice in a dichotomous key is the entries "a. Flower color is red; aa. Flower color is blue" that indicate two different response types.

increase soil erosion                                             reduce soil erosion

cattle grazing                                                         hydroseeding

deforestation                                                         contour plowing

                                                                                planting vegetation

plant roots basically hold the top soil

together and stop soil erosion because

in such situation top soil is not removed

during flood but cattle grazing causes

soil erosion because cattle consume the

grasses and herbs and top soil is exposed.

same situation occurs because of

deforestation, the trees and plants are cut

down to expose top soil which causes soil

erosion