Answer:
a. Random assignment
Explanation:
Random assignment: The term random assignment is defined as the implementation of chance procedures in various psychological experiments to make sure that every single participant or subject in the experiment gets equal opportunity of getting assigned to any of the group used in the experiment, for example, the experimental group.
Example: In any psychological experiment, all the subjects get the equal opportunity of getting assigned in either the experimental group or the control group.
In the question above, the given statement refers to the random assignment.