TOEFL Listening: TPO-TOEFL听力TPO - HAD64O9M9C37I7O4R$

What did researchers conclude from their study of sauropods and gastroliths? A. That gastroliths probably helped sauropods to store large quantities of plant material in their stomachs. B. That sauropods probably used gastroliths to conserve energy. C. That sauropods may not have used gastroliths to aid their digestion. D. That sauropods probably did not ingest any stones.