Choose the correct answer:I. From bones found in the United States we have learned that many, many animals no longer found in the world once made their homes here. We say that these animals are "extinct." Sometimes, workers find their bones in pits from which rock and coal have been dug. Other workers who make way for railroad tracks and workers who dig pits for the basements of new buildings sometimes uncover them. Nowadays, scientists know where to look for them. Huge fishes and enormous reptiles swam in the water. On the shores roamed tigers with tusks, very big lions, great bears, rhinoceroses covered with wool, and herds of hippopotamuses, as well as horses only as big as a fox.B. "Extinct" means -"