我是这么理解的:题目问的是what evidence indicates that aggression in animals is related to the hypothalamus) U% ?% f. y7 f6 c3 ^
. `5 t# e2 c8 {( p/ O
是要aggression-hypothalamus之间联系的证据3 J% G0 B, M% @0 H3 d0 J$ a
2 P; U; Q8 u9 f
而文中的逻辑关系应是:electrical stimulation-hypothalamus-aggressive behaviors,选项2是说artificial stimulation results in aggression,这个逻辑关系跳跃了一级,而且不够general(如答案所说),并非题目所要的evidence。题目所要的evidence是between hypothalamus and aggression的,所以选项3才是答案。。