阅读aggression一文当中的问题

wuhy08UID: 2671269

求做过的牛人解答：
Paragraph 2: The Biological Approach. Numerous biological structures and chemicals appear to be involved in aggression. One is the hypothalamus, a region of the brain. In response to certain stimuli, many animals show instinctive aggressive reactions. The hypothalamus appears to be involved in this inborn reaction pattern: electrical stimulation of part of the hypothalamus triggers stereotypical aggressive behaviors in many animals. In people, however, whose brains are more complex, other brain structures apparently moderate possible instincts.
1. According to paragraph 2, what evidence indicates that aggression in animals is related to the hypothalamus?
○Some aggressive animal species have a highly developed hypothalamus.
○Artificial stimulation of the hypothalamus results in aggression in animals.
○Animals behaving aggressively show increased activity in the hypothalamus.
○Animals who lack a hypothalamus display few aggressive tendencies.

我想选2，答案选3.读了几遍文章怎么也看不出门道。2是说人工刺激H能得到animal的aggression,3是说动物的aggression得到了H的增加
原文中说：In response to certain stimuli, many animals show instinctive aggressive reactions
求解释吧~