Evaluating the author's purpose when reading an informational text is important primarily because it can help a reader determine what an author wants them to learn from the text. Understanding the author's intent—whether to inform, persuade, entertain, or explain—can guide the reader in interpreting the information accurately and in context.
While the other options are relevant to understanding an informational text, they are not the central reason for evaluating the author's purpose. Knowing the intended takeaway from the text enhances comprehension and critical analysis, allowing readers to assess the reliability and relevance of the information.