Answer: A) the author’s knowledge, C) the author’s opinion, D) the author’s worldview and E) the author’s experience.
Step-by-step explanation: A viewpoint is the particular way a person sees the world, we can also say that it is a person's distinct perspective or individual attitude about things. An author's viewpoint will influence his/her ideas and way of writing. There are many factors that can affect an author's viewpoint, from the given options those factors are the author’s knowledge , the author’s opinion , the author’s worldview and the author’s experience .