According to the passage, in the Dewey Decimal System, all books are categorized into

This question is asking for a detail stated in the passage. The Dewey Decimal System is outlined in the first paragraph, which states that titles are arranged "into 10 classes, with 10 divisions each, with each division having 10 sections." "One general class" and "One general class and one division" each omit at least one part, and choice "One general class, including AG" would be found in the Library of Congress Classification.