This can be looked at in two ways. It can be looked at as an answer, "Where is the tree." "Over the Cracks in the sidewalks", or it can be looked at as a sentence standing alone which is what I believe is happening.
It is A.) Sentance fragment
The best sentence that shows the lack of interest of white Americans in the lives of African Americans and other minorities is “They shy away from romantic stories about Negroes and Jews because they feel that they know the public indifference to such works, unless the story or play involves racial tension.”
In this sentence of the excerpt we can infer publishing houses will not sponsor books or publications based on stories about minorities and black people because the public is not interested in those stories and would not buy books related to topics that have minorities as main characters.