Final answer:
Frontal lobe abnormalities are associated with higher levels of aggressive behavior, as they can impair the regulation of emotions and impulses, leading to increased aggression.
Step-by-step explanation:
The question is asking which of the following is associated with higher levels of aggressive behavior. Based on the information provided and existing research, option d. Frontal lobe abnormalities is associated with higher levels of aggressive behavior. Research has shown that alterations in serotonergic function in the brain can lead to increased aggression. The frontal lobes, especially the ventromedial prefrontal cortex, are significant in regulating emotions and impulses, which includes aggressive behavior. When there are abnormalities in these areas, such as damage or dysfunction, it can result in impaired judgment and increase the likelihood of aggressive behavior. In contrast, while there have been discussions about hormones such as testosterone and aggression, studies have shown that there is no clear relationship establishing testosterone as a direct cause for aggressive behavior, and these studies often face methodological issues.