The correct option is A it/she/me/which
We can use it as an ‘empty’ subject or as an ‘empty’ object. It is ‘empty’ because it doesn’t refer to anything in particular, here to introduce the fact. The second blank requires a third person singular feminine subject pronoun "she", the third blank requires a first person singular object pronoun "me", and the fourth blank requires a relative pronoun which will refer to an indefinite object or thing, here, the subject, that is, "which". Hence, Option C is correct. The rest of the options do not adhere to this rule, hence incorrect.