In California, a lack of genetic variation in the Argentine ant has allowed the species to spread widely; due to their being so genetically similar to one another, the ants consider all their fellows to be a close relative and thus do not engage in the kind of fierce intercolony struggles that limits the spread of this species in its native Argentina. 觉得选C不选D是因为句子后面的 in its native Argentina 中的its 决定应该用单数,不用复数