Answer:
C. They have gone to Cleveland for Thanksgiving.
Explanation:
Since the sentence is already in the past tense, it is not possible to use the past tense of the verb in the sentence. And when the "have" form of the verb is in use, it is in the perfect tense, thereby making the adjoining verb to be in the 3rd form of the verb, or the past participle form of the verb. So, here in the sentence, the correct way of writing the sentence will be
They have gone to Cleveland for Thanksgiving.
"gone" being the 3rd form of the verb.
