What is portal system?
a. it is where an organ has a lot of capillaries for better circulation.
b. it is where an organ is supplied with two interconnecting arteries.
c. it is where an artery supplies blood to an organ and immediately returns to the heart.
d. it is where an artery breaks into two sets of capillaries before returning to the heart.
e. it is where two or more branches of an artery supply blood to different organs.

d. It is where an artery breaks into two sets of capillaries before returning to the heart.

Explanation:

A Portal System is where an artery breaks into two sets of capillaries before returning to the heart.

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