Fill in the blanks with the most appropriate words.
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)she/ in is correct as 'is' indicates a specific pronoun and in indicate inside something. The other options are wrong as I , on, and at indicate am, a surface, and a specific location respectively. These uses don't fit in the given question. The correct answer is A)she/in.