To Make Sure That Groups of Participants in an Experiment

Multiple Choice

To make sure that groups of participants in an experiment are not generally different from each other before the experiment begins, the experimenter ____.

A) uses an objective observer to assign participants to groups
B) uses random assignment to assign participants to groups
C) assigns participants to groups by himself or herself without interference by anyone else
D) assigns participants to groups on the basis of an unimportant trait such as hair color