Yes that sentence is perfectly fine.
The answer would be the last one, leave it as is. B and C change the meaning of the sentence entirely, while A sounds unnatural and is too verbose.
Hope this helps! :)
The answer to your question would be that the sentence that contains a verb tense shift error is the following one: Kristoff worked hard on his diet, but he could not resisted snacking. That is, the answer would be B.
A verb tense shift refers to the change from one verb tense to another within a sentence or paragraph. In this case, the verb "resisted" should be in the bare infinitive form as it is preceded by the modal "could". That modal is already related to the past tense used in the first part of the sentence.
B: the desire to prove to others that you’re right can lead to extreme actions.
In the story, the lawyer and the banker get into an argument about whether or not life imprisonment would be more humane than capital punishment. The banker challenges the lawyer to a bet stating that the lawyer must remain in isolation for 15 years. To prove that he is right, the lawyer takes the bet. The desire to prove himself correct leads the lawyer to take the extreme action of giving up everything and living a life locked up in solitude.
Lady Montague dies after her son's exile. It is thought that she died of grief, as Montague states:
Prince. Come, Montague; for thou art early up, To see thy son and heir more early down. Montague. Alas, my liege, my wife is dead to-night;Grief of my son's exile hath stopp'd her breath: What further woe conspires against mine age?
