Random assignment can be described as a research method:

used to balance the independent and dependent variables.
no longer used because of its unpredictability.
increasing the likelihood that the experimental group and control group will be different.
used to balance the control and experimental groups

Either A or D. I'm leaning toward D.

I agree -- D.

Random assignment is a research method used to balance the control and experimental groups. It involves randomly assigning participants to either the control group or the experimental group. The purpose of random assignment is to ensure that there are no systematic differences between the groups before the treatment or intervention is applied. By randomly assigning participants, the likelihood of the control and experimental groups being different is increased. This increases the internal validity of the study, as it helps to reduce the impact of potential confounding variables. Random assignment is considered a standard practice in experimental research because it helps to ensure that any differences observed between the groups can be attributed to the treatment or intervention being studied, rather than other factors. It should be noted that random assignment is different from random sampling, which involves randomly selecting participants from the target population.