Question: Of Thee I Sing: A Letter to My Daughters is a children's book by former United States President Barack Obama, the stories of thirteen Americans are told in the book, including Jackie Robinson, who was an American professional baseball second baseman who became the first African American, to play in which organization?
Sentence (from "Jackie Robinson"): When the Dodgers signed Robinson, they heralded the end of racial segregation in professional baseball that had relegated black players to the Negro leagues since the 1880s.
Relevant evidence: No