Dr Gordon Finds That Heroin-Addicted Adults Almost Always Smoked Cigarettes

Dr. Gordon finds that heroin-addicted adults almost always smoked cigarettes and drank alcohol when they were young adolescents. Knowing this strong association we can conclude that ________

A) cigarette smoking causes drinking, which causes heroin addiction.
B) if cigarette smoking and drinking could be stopped in adolescence, heroin addiction would be stopped too.
C) heroin addiction is caused by the same factors that cause early smoking and drinking.
D) there is an association among the variables, but no causal inferences should be drawn.