Kim was reading about the Jurassic period in the Mesozoic era. She was especially interested in the rise of the dinosaurs. How did the second mass extinction and the loss of the dinosaurs affect the remaining populations of mammals that did survive?
A. With less competition, the remaining mammals had to move from their established habitats.
B. With less competition, the remaining mammals had more food, water, and habitats
C. With more competition among the other kinds of populations, the mammals had to struggle to survive.
D. With more competition among the other kinds of populations, the mammals were able to thrive.