Researchers found that in the United States and Canada,homicide rates doubled over a time in which TV with violent programming was introduced.This finding does not prove that viewing violence on TV causes aggression because

A) the finding could not be replicated in another country.
B) the researchers randomly assigned viewers to watch either violent or nonviolent programming.
C) the research finding involved correlational evidence.
D) the research participants knew they were part of an ongoing TV viewing study.

The research finding involved correlational evidence, which means that a correlation was found between the introduction of violence on TV and an increase in homicide rates but this does not prove causation. There could be other factors that contribute to both the increase in violence on TV and the increase in homicide rates, or there could be a reverse causality where increased violence in society leads to more violent programming on TV. Randomly assigning viewers to watch either violent or nonviolent programming (B) would provide experimental evidence and strengthen the claim that viewing violence on TV causes aggression, but this was not done in the research. The finding not being replicated in another country (A) or the participants knowing they were part of an ongoing TV viewing study (D) are not relevant to the validity of the finding.