What type of content does "The Horn Book" periodical focus on?

"The Horn Book" is a well-established periodical that specializes in children's and young adult literature, providing critical reviews and insights on various books targeted at these age groups. It also covers aspects related to authors and illustrators, offering readers valuable information on noteworthy titles and trends within the genre. This focus makes it an essential resource for educators, librarians, and parents who are seeking high-quality literature for young readers.

The other choices involve different subject areas that do not align with the primary mission of "The Horn Book." Content geared toward adult fiction and non-fiction reviews, educational policy, or specific formats like graphic novels and comic books falls outside the scope of what this periodical addresses. Thus, the emphasis on children’s and young adult literature in "The Horn Book" is what solidifies option B as the correct answer.