Fill in the blank with the relevant 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)for is correct as it is used to express intention. The other options are wrong as with, at, and in indicate inclusion, a specific location, and a location inside an area respectively. These uses don't fit in the given question. The correct answer is A)for.