To Conduct an Experimental Study of the Causal Effect Smoking

Multiple Choice

To conduct an experimental study of the causal effect smoking has on physical health, we would have to

A) find a group of smokers and compare their physical health to a group of nonsmokers.
B) randomly assign some people to a smoking condition and some others to a control condition.
C) compare the physical health of a heavy smoker to the physical health of a person who has never smoked.
D) teach one group of people to adopt good health habits and see if they are more likely to begin smoking than a group of people who have not been taught good health habits.