Respuesta :
It would be no error because B or C wouldn't be past tense and A is present :)
Answer:
No error
Explanation:
The verbs of the dependent clause: until Henry got up and left indicates us that the sentence refers to a past tense, therefore, the main or independent clause, they KEPT talking on and on about the wedding, which it's closely associated to the dependent clause should be in past tense too. And since both the past form and past participle of the verb "keep" is "kept", "kept" is the correct form of the verb and the sentence has no error.