You need to answer a given question containing a blank (_). Your answer must be one of the two objects mentioned in the question, for example "trophy" and "suitcase". Your answer must not contain a word that is not present in the question. Please don't use articles (e.g., the, a) before the answer.

[Q]: Since it was a beautiful day, his friend invited him to the park to play frisbee. The _ was flying.
[A]: frisbee


[Q]: John dusted the furniture in his room with a towel and it got the _ dirty.
[A]: towel


[Q]: The librarian removed the books from the shelves and put them into the cart. The _ were now lighter.
[A]:
shelves