Selection Biases Are LEAST Likely to Be a Problem When

Multiple Choice

Selection biases are LEAST likely to be a problem when

A) researchers randomly assign participants to conditions of the independent variable.
B) researchers randomly assign one pre-existing group (such as children in classroom A) to be their experimental group and those in another pre-existing group (such as children in classroom B) to be their control group.
C) research participants are allowed to choose whether they want to be in the experimental group or the control group.
D) volunteer participants serve as members of the experimental group while non-volunteers from the same population serve as members of the control group.