Answer: D. : to show that there had been no fire drills at the factory.
Step-by-step explanation:
In the "Bella" section, the author included the detail that "Bella didn't know what a fire drill was" because there had been no fire drills at the factory.
Since a fire drill hasn't ever taken place, Bella had no idea about what it was. The author including the details wasn't to show that Bella wasn't as educated as Jane nor was it to explain the reason for the spread of the fire.
Therefore, the correct option is D