Which factor cannot result in dog’s stress? ( )

参考解析：

第四段表明研究发现，狗和主人的压力水平是一致的:主人压力越大，狗的压力也越大。The effect was even more pronounced if the dogs was female or if it took part in agility competitions with its owner.如果这些狗是雌性的，或者它们和主人一起参加敏捷活动，这种效果会更加明显。C提到；第五段，Previous research has found that cortisol in humans and their dogs can rise together in the short term, especially when competing.此前的研究发现，人类和他们的狗狗体内的皮质醇水平可以在短期内同时升高，尤其是在竞争时。A提到；第六段，The personality of the owner seemed to play a role to.主人的个性似乎起了作用。提到D。而B主人的同伴没有提到。故本题正确答案选B。