Fill in the blank with a suitable preposition:
A preposition is a word which comes before a noun or a pronoun and establishes a relationship between the elements of a clause or words. Option B)opposite is correct as it is used to indicate a position facing something. The other options are wrong as besides, on, and of means in addition to, indicate a surface, and possession respectively. These uses don't fit in the given question. The correct answer is B)opposite.