After the Drought of the 1930's Farmers in the Great

After the drought of the 1930's farmers in the Great Plains were encouraged to plant rows of trees across fields to decrease soil erosion.How would this reduce soil erosion?

A) Tree roots would retard runoff and prevent erosion.
B) The trees can serve as windbreaks to slow wind erosion.
C) The trees helped shade the ground,retaining moisture.
D) The trees had no effect; they were just used to improve the land appearance after the great depression.