"Why did Leonard decided not to go to the lecture?" is a a question because it is asking why, therefore it should have the question mark.
I think that the best choice for this would have to be Paragraph 6, I could be wrong but I'm pretty sure I'm not. The reason I think that paragraph is the correct option is because it provides more detail, but what really sold me is the line that says "....and enable African Americans to better integrate into American society as a whole.” That shows that they are given opportunity to show off their works and make a better living for themselves, which is exactly what this question is asking/looking for.
“Artists held the belief that through intellect, literature, art, and music, their work could challenge racism and enable African Americans to better integrate into American society as a whole.” (Paragraph 6)
The preposition in this case is From while the prepositional phrase is From China as it consists of the preposition from and the noun China.
