Suppose that we are considering two research studies from a country called Freedonia. Research study A reported that, based on a survey of a representative sample of 2,000 Black men in Freedonia, Black men who had Black doctors had better health outcomes, compared to Black men who had White doctors. Research study B reported that, based on a randomized experiment with a representative sample of 1,000 Black men in Freedonia, Black men who had been randomly assigned to Black doctors had better health outcomes, compared to Black men who had been randomly assigned to White doctors. Which research study has a higher internal validity for testing whether average health outcomes for Black men differ depending on whether their doctor is Black or White? A.Research study A B.Research study B