Final answer:
The word 'scoff' completes the sentence as it describes an act of expressing disdain or contempt for authority, fitting the context of someone facing consequences for breaking the rules.
Step-by-step explanation:
The correct word to fill in the blank in the sentence "He broke the rules and scoff all authority, and now he has to pay." The sentence would then read: "He broke the rules and scoffed at all authority, and now he has to pay." This indicates that the person not only broke the rules but also treated authority with disdain or contempt. The provided examples all portray an attitude of defiance and disregard for rules or laws set by an authority, much like the student in the question who is facing consequences for his actions.