The only possible answer to this question is B. The Warren Commission was a commission that was set up to investigate the assassination of Pres. John F. Kennedy. There was a great deal of speculation at the time (as there still is) that the killing had been the result of some sort of conspiracy. The Warren Commission found that there was no basis for such beliefs.
The commission was headed by (and named after) Chief Justice Earl Warren of the US Supreme Court. He had been the Chief Justice for the Brown v. Board of Education case that banned segregation in schools, but this commission had nothing to do with that issue.