I believe the answer would be B.
Explanation:
Animals lived in the water during the Mesozoic and on land in the Paleozoic. Animal complexity increased during the Paleozoic while the first flowering plants appeared in the Mesozoic era. ...
The Paleozoic era, not the Mesozoic era, had the first dinosaurs. The first mammals emerged in the Paleozoic era, not the Mesozoic era. The Mesozoic era, not the Paleozoic era, had the first animals with shells.
Answer:
Sure grass. And there is a lot of grass. Compete with wild horses, wild pigs, wild goats, wild "golfer's who are way off the fairway. Wild deer are in the forests, wild goats in the hills so buffalo and horses manage the plains and the back nine. So much grass there was no competition...with the wild rabbits. Grass continues to grow. The buffalo move to greener pastures once they mowed down the other fields. When there were Millions of them, they were not starving.
Explanation: Got this from somewhere hoping it helps!