To Cut Costs, a Local Town Stopped Adding Fluoride to Its

Multiple Choice

To cut costs, a local town stopped adding fluoride to its water supply. After the change, local dentists noticed a 25% rise in their number of patients. Clearly, removing fluoride had negative effects on dental health in the town.
The argument depends on assuming which of the following?

A) At least some of the dentist visits were due to a decrease in fluoride intake.
B) Most of the people in the town always drank from the water supply.
C) Cutting the fluoride supply was an effective way to reduce costs.
D) A 25% rise is an abnormally high change in the number of dental patients.
E) Local dentists always keep meticulous records on their numbers of patients.