GRE Reading Comprehension: OG/PP2-GRE阅读OG/PP2 - F63N5BFGA91IZ14AP

According to the passage, improvement in brain function among early large mammals resulted primarily from which of the following? A. Interplay of predator and prey B. Persistence of free-floating awareness in animals of the grasslands C. Gradual dominance of warm-blooded mammals over cold-blooded reptiles D. Interaction of early large mammals with less intelligent species E. Improvement of the capacity for memory among herbivores and carnivores