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 A)in is correct as it indicates inside something. The other options are wrong as on, by, and no preposition indicate a surface, usage, and that there is no of using a preposition in the given sentence respectively. These uses don't fit in the given question. The correct answer is A)in.