The correct answer is: to explain the main idea of a section.
The correct answer is "to explain the main idea of a section." Headings in an informative text are used to provide a concise summary or main idea of the content that follows. They serve as a guide for readers, helping them navigate and understand the organization and structure of the text. By reading the headings, readers can quickly identify the main topics and subtopics of each section, which helps in comprehending the overall message of the text. To determine the purpose of headings in an informative text, it is important to analyze how they summarize and introduce the content that follows.