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 D)of is correct as it is used to express an amount. The other options are wrong as from, at, and off indicate a source, a specific location, and removal of something respectively. These uses don't fit in the given question. The correct answer is D)of.