Researchers divided a group of people on the basis of their smoking status (smokers and non-smokers) and followed them for 20 years to see if they developed lung cancer. This is an exampleof what type of epidemiological research design :a. Cross-sectionalb. Cohortc. Case-controld. Retrospective

A) Cross sectional research

Explanation: Cross sectional research usually involves

different groups of people who differ in the variable of interest but share other characteristics, such as socioeconomic status, educational background, and ethnicity. Cross-sectional research studies are often used by researchers studying developmental psychology. Like in this case of smokers