Answer:
B. By concentrating on the realistic elements of the story
Step-by-step explanation:
Remember, the term reader's suspension of disbelief refers to a process when readers decide to keep aside or suspend their disbelief; thereby accepting the fictional elements of a story as though it is real.
So when an author concentrates on the realistic elements of the story, he thus encourages his reader even further to suspend their disbelief in the story.
For example, instead of concentrating on how a character dreams about having wings that fly [which is unrealistic], the author focuses on a natural tragedy such as the death of a character.