Final answer:
The sentence that should be added is 'I gulped down my food, grabbed my bus card, and pecked my mother on the cheek as I raced out the door.'
Step-by-step explanation:
The subject of this question is English, and it is at the high school level.
The sentence that should be added after sentence 6 to most effectively move the plot forward is: I gulped down my food, grabbed my bus card, and pecked my mother on the cheek as I raced out the door. This sentence shows the protagonist's eagerness to get to work and sets up the next part of the story.
The other options do not serve the purpose of moving the plot forward or connecting to the protagonist's excitement about the new job.
Learn more about Plot development in a personal narrative