The correct answer is II) subheadings .
The feature that appears predominantly within the text itself is subheadings.
Writers consider subheadings as mini headings that help to capture the attention of the reader as well as to maintain the attention during the reading. It also helps to give structure to the text to make it more clear an easy to read and understand. It is very important that the subheading is attractive and says something relevant for the reader to pay attention to it and continue reading. In this case, the feature that appears predominantly within the text itself is subheadings.