Final answer:
In narrative writing, sentence B, 'Doctors have concluded that the new vaccine will be a boost to our medical arsenal,' would not belong because it is a factual statement.
Step-by-step explanation:
In narrative writing, the focus is on telling a story and engaging the reader through characters, plot, and setting. Sentence B, 'Doctors have concluded that the new vaccine will be a boost to our medical arsenal,' would not belong in a narrative writing piece because it is stating a factual statement rather than describing a scene or developing a story.