题目解析:
该段落没有给出将领土争端作为聚集的理由。 所有其他答案都给出了:Clumping often results from the irregular . distribution of resources...; Clumping may also be associated with mating, safety... Crane flies, for example, swarm in great numbers, a behavior that increases mating chances, and some fish swim in large schools so they are less likely to be eaten by predators.