Critical Reasoning (CR) | Re: A sudden surge in the rate of reported cases of a certain disease in

A sudden surge in the rate of reported cases of a certain disease in Aquaville has resulted in investigations that revealed that in the past year, the level of pollutants in Aquaville’s fresh water source has increased manifold. Medical researchers have hypothesized that this polluted water is responsible for the increased incidence of this disease.
Each of the following provides additional support for the researchers’ hypothesis EXCEPT:

A) Towns with geographic and demographic characteristics