Which of the following HAVE BEEN (prior to 2022) considered by the Court in our cases to be "compelling" interests that the state may strive to achieve through race-based or race-conscious regulations?
a. Seeking to correct general past discrimination
b. Seeking to provide educational diversity
c. Seeking to correct a recent, specific instance of discrimination by the institution in question
d. Seeking to provide a racial balance in key institutions that matches the population
