Researchers are curious if there is a connection between childhood cancer rates and living near power lines. What could be a viable way to investigate this relationship?
I. Randomly select 200 children and move half of them near power lines while ensuring the other half de not live near power lines then compare cancer rates.
II. Randomly select 100 children who live near power lines and another 100 children who do not live near power lines then investigate cancer rates of the respective groups.
III. Randomly select 100 children who have and another 100 children who do not have cancer and compare where the children live.