Final answer:
A research study comparing the risk of developing lung cancer between smokers and nonsmokers would be an example of an observational study.
Step-by-step explanation:
The research study comparing the risk of developing lung cancer between smokers and nonsmokers would be an example of an observational study.
An observational study measures characteristics in a sample without manipulating variables. In this case, the researchers would observe and gather data on the smoking habits and lung cancer status of both smokers and nonsmokers. By comparing the two groups, they can determine the association between smoking and lung cancer.