Answer:
I would say the answer is C. The rest seem to be just normal objects. C seems to be more than just an object and more of a symbol of something happening (to a character.)
A. The pear seems to be more of just an object used to illustrate how the violin is crafted masterfully.
B. The boardwalk is just a place and seems to have no meaning other than it's commonplace for the action to happen.
C. The plant seems to have a meaning. The wilting of it indicating how neglectful a character, it doesn't just seem to be like a normal everyday object. It seems to mean something a little more to the story and is most likely a symbol of how neglectful the character is.
D. The artifact is just shown to be acquired and that's it.
So, C seems to be the best answer.
Ask me any questions if you're confused :)