Answer:
Well, it's up to you.
Maybe an ending could be that the narrator made new friends, had a blast and went home smiling.
Another could be that they made enemies and was bullied, and went home wanting to never set foot in the school again.
Explanation:
The case type pronoun that is required to complete the sentence would be A) nominative. It is the subject case, and since we need a subject here, nominative is the option we have to use. For example:
They and the other vaulters have been training for months.
<em>They </em>is a nominative personal pronoun.
Possessive would be <em>theirs, </em>and as you can see, it doesn't fit.
Objective would be <em>them, </em>and it is also incorrect.
Antecedent just means a pronoun.