Which of these was an effect of the U. S. Supreme Court ruling in Plessy v. Ferguson?

Ferguson, 163 U.S. 537 (1896), was a landmark decision of the U.S. Supreme Court that upheld the constitutionality of racial segregation laws for public facilities as long as the segregated facilities were equal in quality, a doctrine that came to be known as "separate but equal".

a) which ethnic groups live in this community?

i just took test

a factory opens that mass-produces light bulbs.

explanation:

not sure if that's an answer to your questions but this is an example! : )