1. To a greater or lesser extent, all of us have learned aggressive responses.
2.We are each a potential aggressor.
3.A number of conditions have been found to stimulate aggression. 4.For one thing, pain–both medical and physical–heightens aggressiveness.
5.Any decidedly hurtful event, whether a big disappointment, a personal insult, or a physical pain, can incite an emotional outbrust.
6.Environmental irritants can also stimulate aggression.
7.The most–studied is heat.
8.Studies have found that, compared with students who answered questionnaires in a room with a normal temperature, those who did so in an uncomfortably hot room (over 90°F) reported feeling more tired and aggressive and expressed more hostility toward a stranger they were asked to rate.
9.A third condition, one that especially provokes aggression, is attacks by another.
10.Experiments confirm that attacks bring counterattacks, especially when the victim perceives the attack as intentional.
11.Finally, crowding–the feeling of not having enough space–can be stressful.
12.The stress experienced by animals allowed to overpopulate a confined environment produces heightened aggressiveness.
13.And it is undeniably true that dense urban areas suffer higher rates of crime and emotional distress.

How many major supporting details are in this passage?
a. Three
b. Six
c. Five
d. Four