Why B over C?

The scholars say Marshall’s early cases were “necessary forerunners” for Marshall’s successful argument in Brown v. Board. That word necessary is crucial — it means that without Marshall’s early cases, Marshall would not have been able to deliver a successful argument in Brown v. Board. Shelley v. Kraemer is one of those early cases. Therefore, the scholars would have to agree that without Marshall’s argument in Shelley, the Supreme Court probably wouldn’t have ruled in his favor in Brown v. Board. (C) is wrong because the legal scholars never said that Marshall’s argument in Shelley was necessary for overturning the Court’s earlier doctrine that “excused private dealings from the legal requirement for equal protection of citizens under law.” Maybe the Court would have overturned this doctrine based on the arguments made by Marshall or someone else in some other case.