The correct option is B by
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 C)by is correct as it is used to express a location near or by the side of. The other options are wrong as on is used to indicate a surface, in is used to indicate a position inside an area, and with is used to indicate inclusion. These uses don't fit in the given question. The correct answer is C)by.