Which of the following advertising media preselects its readership through the nature of its content?

The advertising medium that preselects its readership through the nature of its content is the magazine.

Magazines are designed to cater to specific interests and demographics, meaning they often attract readers who are interested in particular topics or subjects. For instance, there are magazines on hobbies like photography, fashion, technology, sports, and many more. Because they focus on specific themes, they naturally draw in an audience that is interested in those areas. Advertisers can use magazines to reach a target audience that aligns with their product or message.

In contrast, other media such as billboards, handbills, and newspapers are generally more broad and do not specifically tailor their content to a particular interest group. For example, newspapers cover a wide range of topics like news, sports, and entertainment, reaching a more general audience. Billboards and handbills aim to capture anyone who happens to see them.