Random Assignment of Participants to the Various Groups in an Experiment

Multiple Choice

Random assignment of participants to the various groups in an experiment

A) guarantees that the independent variable will affect the dependent variable.
B) maximized the probability that extraneous variables will NOT have a differential effect on the various treatment groups.
C) is essential if you want to generalize your results to the population.
D) is very difficult to do and is therefore not commonly done.