To answer this question, we need to understand possessive pronouns.
The correct answer is B) our.
Option A) us - This option is incorrect because "us" is a pronoun used as an object, not a possessive pronoun.
Option B) our - This option is correct because "our" is a possessive pronoun that shows ownership. It is used to indicate that the school belongs to us.
Option C) ours - This option is incorrect because "ours" is a possessive pronoun that is used without a noun. For example, "The school is ours."
Option D) mine - This option is incorrect because "mine" is a possessive pronoun that is used to indicate ownership for a singular noun. For example, "The school is mine."
Therefore, the correct answer is B) our.