According to the minneapolis, minnesota, study, of the top 10 locations police were called, half were bus depots bars or places alcohol was served malls vacant houses

The answer is: bars or places alcohol was served
Alcohol would impair people's ability to restrict their own actions, which often led them to loosen their behaviors.
This increase the likelihood of things such as verbal confrontation or physical confrontation from occurring that would often involve polices to calm it down.

Where are the choices?