Which author's purpose attempts to convince the reader?
C). Persuade.
If the author's purpose is to convince the reader, they are trying to persuade them. The definition of persuade is: "to cause people to do or believe something..." (Cambridge Dictionary). So, they are trying to convince the reader to do something.
For example, if the author writes an article about volunteering at animal shelters, The author is trying to convince, or persuade, the reader to volunteer at the animal shelter.