Answer:
A claim
Explanation:
I'm not 100% sure since there can be a lot of different answers for fill in the blank questions like this, but a claim is a statement, assertion, or opinion that isn't necessarily fact based, so you would need to prove it.
(Hopefully that helped!)
I would say that the correct answer is B, concerned. A doesn't apply, he isn't really preoccupied with something over something else, and C doesnt completely make sense with the passage. And Tom isn't horrified, he doesn't seem to be reacting too much at all, other than just seeming concerned.
analyzing how specific details are connected.