In Grutter v. Bollinger (2003), the Supreme Court ruled that the University of Michigan Law School's affirmative action policy was constitutional, since race was used only as a plus factor and not a quota. Therefore, the correct option is D. The case involved a challenge to the University of Michigan Law School's affirmative action policy, which considered race as one of many factors in admissions decisions. The Court held that the policy was constitutional because it served a compelling state interest in promoting diversity, and because it was narrowly tailored to achieve that interest. The Court emphasized that the policy did not use quotas or set-asides, and that race was only one of many factors considered in admissions decisions.