Answer: B. The decision of Plessy v. Ferguson made racial segregation more widely practiced and accepted in the United States
Step-by-step explanation:
The main idea of this passage was to show how the Supreme Court's decision in the aforementioned case made segregation in the United States legal and therefore more widely practiced and accepted.
This was the main idea because the passage revolved around it by first giving a background on how the idea was born and then showing the effects of the decision and finally its conclusion.