结论:participating in social interaction—suffices.
原因:Evidence to this effect comes from a study showing that the more social contact people report, the better their mental skills.同向the+比较级并不能表示因果关系,只能表示同向关系
削弱它可以是有一个其他的因素,同时导致的因果的发生,也就是B选项的 Many medical conditions and treatments