According to the passage, which of the following best accounts for the apparent bias in antelope-migration direction? A. Warm-adapted antelope species are rarely able to tolerate cool habitats, whereas cold-adapted antelope species usually can tolerate warm habitats. B. During global warming periods, land bridges, when present, lack habitats suitable for sustaining warm-adapted antelope species. C. Under most climatic conditions, Africa offers a larger number of suitable antelope habitats than does Eurasia. D. Many more species of antelope have originated in Eurasia than have originated in Africa. E. Land bridges are more likely to exist when climate change favors migration to warmer climates than when climate changes favors migration to cooler climates.