Text features can be very helpful in delineating an author's argument, primarily because they often highlight important information and structure that aids comprehension. Among the options you've provided, the most accurate statement is:
Text features reveal main points to the reader.
Text features such as headings, subheadings, bullet points, charts, graphs, and bold or italicized text can guide the reader to understand the key points and structure of the argument. They help to summarize information, indicate the organization of the text, and draw attention to significant evidence or claims made by the author.
The other options do not directly reflect the primary role text features play in understanding an author's argument.