<span>The correct answer is III. The author's purpose is the reason why a text has been written, which usually falls under one of three categories: persuade, inform, entertain. Other forms of purpose usually fall under one of these. Examining the details of the text, for example, the type of language used and any accompanying images will help a reader work out the author's purpose. </span>
I would choose a. Simply because the author talks about it as if it's all that really ever existed and that nature cannot take over what it is not. However, it goes on about seeing how erosion and rot can affect such things and tries to compare it to things in nature as if it were nature itself.
