For Questions , Use the Following Narrative

Essay

For Questions , use the following narrative
Narrative: Aspirin and polyps
A study done by the Ohio State University Medical Center examined whether or not taking an aspirin a day would help colon cancer patients reduce the chance of getting subsequent colon polyps.635 patients with colon cancer participated; 317 of them were randomly assigned to the aspirin group, and the other 318 patients were assigned to a placebo (non-aspirin) group.54 patients in the aspirin group developed subsequent polyps, compared to 86 patients in the non-aspirin group.Many confounding variables were controlled for in this well-designed randomized experiment.
-{Aspirin and polyps narrative} Which variable is the explanatory variable and which is the response variable in this study?