The correct answer is D. The term defined as "a legal doctrine that permitted racial segregation in public facilities" was Separate But Equal.
Explanation:
Separate But Equal was a juridical doctrine of the constitutional right of the United States that justified and allowed racial segregation, understanding that it did not suppose a violation of the Fourteenth Amendment of the Constitution, guarantor of an identical protection under the rule of law for all citizens. According to this doctrine, the government could allow public or private sectors such as services, facilities, accommodations, housing, medical care, education, employment and transportation could be separated by race, since the quality of each of these services would be same.
This doctrine was confirmed in the judgment of the case Plessy v. Ferguson of 1896 by the Supreme Court of the United States, which legalized racial segregation at the state level. Although the segregationist laws already existed before the case, this decision eventually led to segregation in the states in the era of the Jim Crow Laws, which had in fact begun in 1876, restricting the rights and civil liberties of millions of African-Americans without any pretension of equality during the period of Reconstruction. In subsequent years 18 states adopted segregationist laws, restricting the rights of blacks.
This doctrine only began to fall after a series of Supreme Court rulings in the mid-twentieth century, culminating in 1954 with the ruling in Brown v. Board of Education. But, the end of segregationist laws in the United States would be a longer process, going through the 1950s, 1960s and 1970s, involving many decisions of state and federal courts, as well as actions by the legislative branches.