QueenNerdy889 QueenNerdy889 02-04-2019 English contestada PLZ HURRY IT'S URGENT!!!!! Which word group best completes the sentence without introducing an inappropriate shift in tense? He had been reading a book A. when the thunderstorm is starting. B. when the thunderstorm will start. C. when the thunderstorm starts. D. when the thunderstorm started.