In an Experiment, Researchers Exposed Half the Children to 2

Multiple Choice

In an experiment, researchers exposed half the children to 2 hours of violence on television every day for a month and made sure the other half saw no violence on television at all. At the end of the month, they measured the aggressiveness in the children. The fact that the researchers ensured that some children watched violence on television and others did not is an example of:

A) matched pairs.
B) matched samples.
C) correlation.
D) manipulation.