根据以下材料，回答31-35题
Last month, the Supreme Court reaffirmed that universities can use race in making admissions decisions.Justice Anthony M.Kennedy wrote that "student body diversity" at the modern university was"central to its identity and educational mission."
He's right.But it's also fair to question how well universities are fulfilling this mission, especially in light of the protests that swept U.S. campuses last year.Over the past 30 years,universities have become vastly more diverse.But students of color continue to denounce them as insensitive, inhospitable and hostile to nonwhites.
What can we do about that? Most university administrations have responded to the diversity challenge in a predictable way：by hiring administrators.More than 100 institutions now employ "chief diversity officers". Hundreds of schools offer diversity training and other programming, aimed at changing the overall racial climate on campus.
But there's no strong evidence that these costly efforts have changed anything.Examining nearly 200 studies of diversity training in the corporate and educational world conducted over the past 40 years, psychologist Katerina Bezrukova found no indication that they affected participants' racial attitudes over the long term.
But research did find that students who lived with a member of another race showed significant gains in the comfort levels they exhibited around different groups.They were also more likely to make friends with people outside their own race.
Unfortunately, more colleges are allowing freshmen to choose their own roommates.And, unsurprisingly, almost everyone who does that selects someone of the same race.Many schools are also offering single rooms to freshmen, who happily seize the opportunity to avoid the "hassle" of living with someone else.
So, instead of expending yet more resources on multicultural programming, let's generate multicultural roommate pairings.All freshmen roommates should be randomly assigned.And we should bar or discourag freshmen from taking single rooms.
A study of Ohio State University freshmen found that African American students earned better grades if they had a white roommate than if they had a black one.As one black student suggested, blacks who lived with whites might be motivated to work harder to avoid confirming negative stereotypes about minority academic performance.
Meanwhile, single rooms decrease the odds of students getting to know people different from themselves.They might do so on the Internet, of course, but only in a superficial way that allows either party to disappear whenever he or she feels like it.Living with someone forces you to engage in the messy, unpredictable work of interactions that students call FTF (faceto face) or IRL (in real life).
According to the first two paragraphs, American universities were_______

A expected to have diverse student societies

B expected to enroll racially diverse students

C charged with racial discrimination

D criticized for becoming less diverse