Question

a study following a group of smokers and non - smokers over 20 years and monitoring rates of lung cancer that develops over time is an example of which type of study design?

Explanation:

A cohort study follows a group of individuals over time to observe the development of a disease or outcome. In this case, the study is following smokers and non - smokers (a cohort) over 20 years to monitor lung cancer rates (the outcome).

Answer:

This is an example of a cohort study.