Read the passage.

The Dust Bowl
During the 1930s, extreme drought and high winds made life incredibly difficult in the Great Plains region of the United States. In many areas, rainfall was forty percent less than normal. The soil became extremely dry, and when strong winds blew, they created tremendous dust storms. These so-called “black blizzards” were so thick that they made daylight seem like dusk. During this terrible period, the Great Plains region of the United States was named the “Dust Bowl.” Over the next few years, the drought continued, and the winds created more dust storms. In some places, the drought and high winds lasted for eight years. Many people wondered if the black blizzards would ever end.

Which statement about this paragraph’s main idea is true?
A. There are not enough details to support the main idea.
B. This paragraph’s main idea is implied.
C. This paragraph’s main idea is stated in the topic sentence.
D. This paragraph does not express a main idea.

The topic sentence is the most important sentence in a paragraph. It sets the main hypothesis, the tone, and the general idea of the paragraph. In general terms the topic sentence is at the beginning of the paragraph and often, as in this case, it is the first sentence. As we can see in the extract, the text is giving information about the "Dust Bowl," the phenomenon in which extreme drought and high winds caused grave ecological and economic problems in the Great Plains region of the United States. All this idea is clearly summarized and introduced in the first sentence.

Explanation:

The right answer for the question that is being asked and shown above is that: "During the 1930s, extreme drought and high winds made life incredibly difficult in the Great Plains region of the United States." This is the sentence that serves as the paragraph's main topic sentence.