The correct answer is D.
During the 1930s, extreme drought and high winds made life incredibly difficult in the Great Plains region of the United States.
Step-by-step explanation:
In a paragraph, the topic sentence is the sentence that encloses all the ideas in a paragraph and that summarizes the topic and focus of it; additionally, this type of sentence is usually the first sentence in a paragraph but can be included at the end of the paragraph as well. In the case of the passage presented, this passage includes details such as "In many areas, rainfall was forty percent less than normal", "when strong winds blew, they created tremendous dust storms" and "Over the next few years, the drought continued, and the winds created more dust storms", all these details aim at explaining the Dust Bowl and the effect this has and therefore the idea that encloses these details and summarizes the focus and topic of the paragraph or the idea that is the topic sentence is " During the 1930s, extreme drought and high winds made life incredibly difficult in the Great Plains region of the United States".