Which one of the following words is not an object a preposition?

You're asking about prepositions, but you haven't provided a list of words. Please provide the list of words so I can help you identify the one that isn't an object of a preposition.

For example, you could say:

"Which of these words is NOT an object of a preposition: book, over, in, the, table?"

Once you provide the list, I can tell you which word doesn't fit the description.