In the past year, Harborville has had an unusually high rate of new cases of a certain disease. An investigation revealed that over the past five years Harborville's public water supply has had a high level of pollutants. Medical researchers have hypothesized that Harborville's water is reposnsible for the high rate of new cases of the disease.

Each of the following provides additional support for the researcher's hypothesis EXCEPT:

A. Most of the people afflicted with new cases of the disease had regularly drunk larger quantities of Harborville's water than had other Harborville residents.
B. The same types of pollutants that have been found in Harborville's water have been independently linked to occurrences in other towns of the high rates of this disease.
C. Some of the people with newly diagnosed cases of this disease began to develop the disease before Harborville's water became polluted.
D. The rate of new cases of diseases among Harborville's residents who get their water from private sources is not unusually high.
E. Towns with geographic and demographic characteristics similar to those of Harborville, but without polluted water do not have a high rate of the disease.

OA C

Source: GMAT Prep