An oncologist wants to perform a long-term study on the benefits of eating tomatoes. In particular, she wishes to determine whether there is a significant difference in the rate of prostate cancer among adult males after eating one serving of tomatoes per week for 5 years, after eating three servings of tomatoes per week for 5 years, and after eating five servings of tomatoes per week for 5 years. Help the oncologist design the experiment. Include a diagram to illustrate your design.