Remember that epidemiology can suggest a cause of a disease by telling us who gets the disease. You are an epidemiologist interested in studying a rare type of cancer that is surprisingly common on the (imaginary) island nation of Blefuscu. Your research finds that people who are born on Blefuscu and live there all their lives develop this cancer at a rate of 4%. Conversely, people who are born on Blefuscu but move to another part of the world by age 10 get this cancer at a rate of 0.002%. In the paper you're writing to publish your results, will you suggest that the cause of this cancer is mainly genetic or mainly environmental? Why?
a) Genetic, due to the higher incidence among natives.
b) Environmental, due to the higher incidence among immigrants.
c) Genetic, due to the lower incidence among immigrants.
d) Environmental, due to the lower incidence among natives.