Vance Alexander Is a Professor of Epidemiology and Environmental Medicine

Vance Alexander is a professor of epidemiology and environmental medicine at Washington State University's School of Veterinary Medicine. He and his team reported that they had found an association between the risk of transitional cell carcinoma (TCC) of the urinary bladder in Scotties and the terriers' exposure to lawns treated with commonly used herbicides. The study was based on a survey of owners of 83 Scottish terriers, all of which were about the same age and had bladder cancer. The dog owners documented their terriers' housing, exposure time to the lawn, and information on the lawn treatment used. Those results were then compared to a group of 83 unexposed similarly aged Scotties that were undergoing treatment for unrelated ailments. Dr. Alexander found the occurrence of bladder cancer was between four and seven times higher in the group of dogs exposed to the herbicides. Dr. Alexander stated that Scotties seem to have a genetic susceptibility to this type of cancer. "We choose the Scottish terrier because we had done a previous study to show that this breed had a higher risk of bladder cancer compared to all other breeds-about 18-fold greater risk." What would be considered the control group in this experiment?

A) the Scottish terriers exposed to herbicide
B) the Scottish terriers without cancer
C) any type of dog that does not have cancer
D) all dogs that are exposed to herbicides