GRE Reading Comprehension: JiJing 352-GRE阅读机经352篇 - 96A055NQPU1N1YW5J

The passage suggests that investigators of monkeys social behavior have been especially interested in aggressive behavior among monkeys because A. aggression is the most common social behavior among monkeys B. successful competition for incentives determines the social order in a monkey group C. situations that elicit aggressive behavior can be studied in a laboratory D. most monkeys are potentially aggressive, yet they live in social units that could not function without control of their aggressive impulses E. most monkeys are social, yet they frequently respond to newcomers entering existing social units by attacking them