Billy Shows High Levels of Aggression on the Playground,and His

Billy shows high levels of aggression on the playground,and his mother has attempted to determine the cause of his aggression.She has noted several facts about Billy that she thinks could be contributing to these aggressive displays.Which one of the following demonstrates a chemical cause for his aggression?

A) Billy's father was also very aggressive.
B) Billy's doctor found that Billy has exceptionally high levels of testosterone.
C) Billy's friends are also very aggressive boys.
D) Billy's mother consumed a great deal of alcohol when she was pregnant with Billy.
E) Billy watches a lot of violent cartoons.