its d because Republicans
In a prominent model of self-administration developed by George Koob, rats are allowed to self-administer cocaine for either 1 hour each day (short access) or 6 hours each day (long access).
I believe the answer is :Random sampling
Random sampling refers to select a group of subjects that could be used as sample for a research from a large population. The selection is beind done without any criteria in hope that the sample at least represent the general composition of the population.
