Answer:
The correct answer is "US"
Step-by-step explanation:
"We" and "US" are both personal pronouns but they differ since the first one is a subject pronoun and the second one is an object pronoun.
The personal pronoun "we" is a subject pronoun since it takes place as the subject of a sentence.
The personal pronoun "us" is an object pronoun since it is used, in this case, as the object of a preposition.
In this example, the pronoun "us" is the object of the preposition "for".