Read the following passage and then select the correct answer: According to some sources, more than 30 million adult Americans are unable to read. There are different levels of illiteracy; some adults will be able to recognize a collection of words, while others cannot read at all. Without strong reading skills, it is difficult for people to hold jobs and become productive members of society. To improve our economy, it is imperative that the United States push its citizens to become more literate. Which of the following sentences provides support for the author's claim?