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 example of what type of epidemiological research design

Cohort

Explanation:

Cohort studies refer to a form of medical study which is used to examine the reasons for the disease and to find its relation to the risk factors to medical outcomes. Usually, cohort studies track large groups of people, tracking their susceptibility to such risk variables in order to obtain answers to the potential causes of disease.  

As per the question, researchers observe a group of people based on their smoking habits and tracked them for twenty years to observe its relation to lung cancer reflects the procedure of cohort studies.

absolute poverty the condition of having too little income to buy the necessities-- food, shelter, clothing, health care.

achieved status a social position (status) obtained through an individual's own talents and efforts.

affirmative action the requirement that employers make special efforts to recruits hire and promote qualified members of previously excluded groups including women and minorities.

aggregate a collection of unrelated people who do not know one another but who may occupy a common space--for example, a crowd of people crossing a city street.

agrarian societies societies in which large scale cultivation using plows and draft animals is the primary means of subsistence.

alienation the separation or estrangement of individuals from themselves and from others.

amalgamation the biological as well as cultural assimilation (merging) of racial or ethnic groups.

anomalies in science observations or problems that cannot be explained or solved in terms of a prevailing paradigm.

anomie a breakdown or confusion in the norms, values, and culture of a group or a society. a condition of relative normlessness.

anomie theory the theory suggesting that deviance and crime occur when there is an acute gap between cultural norms and goals and the socially structured opportunities for individuals to achieve those goals.

anticipatory socialization the process of taking on the attitudes values and behaviors of a status or role one expects to occupy in the future.

apartheid the recent policy of racial separation in south africa enforced by leg

explanation:

answer; self-efficacy;