Answer:
Plessy v Ferguson created a standard for racial equality for decades in America.
Step-by-step explanation:
The 1896 Supreme Court case of Plessy v Ferguson was a result of the case between Homer Plessy, a mixed-race man, and the presiding justice Judge John Howard Ferguson. Plessy lost the case, with the judge upholding the constitutionality of racial segregation.
This case not only legalizes and justifies the constitutionality of maintaining racial segregation in public places. It also allows the implementation of the "Jim Crow" laws and allowed states to practice racial segregation. The one effect that is not part of the case is that it created a standard for racial equality in the country.
Thus, the correct answer is the third option.