TOEFL Listening: TPO-TOEFL听力TPO - J53DJ72937PT08V4R$

What can be inferred from the fact that Lechuguilla Cave is no longer forming? A. The cave has stopped attracting visitors. B. The cave no longer contains any limestone. C. The air in the cave is safer to breathe now than it was in the past. D. Gypsum deposits inside the cave are growing thicker.