(1) The Dust Bowl was an eight-year period of drought and dust storms that plagued the Northern and Southern Plains of the United States. The catastrophe lasted from the summer of 1931 to the fall of 1939. The Dust Bowl was the result of poor land management and a lack of rain.
(2) Before the Great Plains were settled, plant and tree roots held the soil in place and prevented the water from running off. Settlers cleared the land, plowed deep into the ground, and planted cotton, wheat, and corn. In 1930, the plains farmers were harvesting bountiful crops. However, overuse of the land sapped it of nutrients needed to support the crops. In the summer of 1931, the decrease in rainfall and poor soil condition caused a lot of the crops to die. Strong winds blew away the dead and weakened plants.
(3) In 1932, the skies became brown and black with clouds of dirt. Deep blankets of dust covered homes, vehicles, and anything else that was out in the open. People and animals died of suffocation and pneumonia. In 1934, the government minimally compensated farmers for their livestock and rid them of the burden of caring for the animals. Masses of people left their homes in search of work and food. Bordering states did not welcome the migrant workers because their own economies and employment opportunities were in decline. Many of the displaced workers and their families lived in makeshift shacks without plumbing or electricity.
(4) In 1935, a conservationist by the name of Hugh Hammond Bennett led a strong campaign for better farming practices and land management. He spoke to Congress and succeeded in getting the Soil Conservation Act of 1935 passed. President Roosevelt also took action to prevent further harm to U.S. lands. The Roosevelt administration educated farmers on techniques to conserve the land. In 1937, the government began paying farmers to use new farming techniques. The farmers received a dollar an acre for trying crop rotation, strip farming, contour plowing, terracing, and other approved conservation methods. Also under Roosevelt's guidance, the Civilian Conservation Corps planted millions of trees between Canada and Abilene, Texas, to create a windbreak and to hold the soil in the ground. These efforts yielded a 65 percent reduction in the amount of soil being carried away by the wind by 1938. Although there was a lot of improvement in the quality of the land, the dry soil failed to produce adequate harvests.
Question: Which sentence could best be added to paragraph 4 as a conclusion?
a
Finally, in 1935, the government took action to end the Dust Bowl.
b
Finally, in the fall of 1939, abundant rainfall ended the Dust Bowl.
c
Finally, in 1937, farmers learned new farming techniques.
d
Finally, the conservation efforts made a difference in 1938.
