Which invention of the Tang and Song Dynasty was the most important?

Which scenario is not an example of one of the primary motivations for bias in media coverage

Which effect did the united states supreme court's decision in plessy v. ferguson have? 1. ending segregation in all public schools in america 2. protecting voting rights for african americans by eliminating literacy tests 3. upholding the rights of all citizens to be treated equally by the government 4. authorizing the system that kept black and white people separated

Louisiana purchase timeline can someone give me the answers, it's due tomorrow.