Answer:
"How would Anderson like to sing on Easter Sunday at the Lincoln Memorial? It would be an outdoor concert, free, open to all—and with no segregation."
Step-by-step explanation:
"Marion Anderson sings" refers to the event when African American singer Marion Anderson was singing on the steps of the Lincoln Memorial.
The concert was performed on Easter Sunday in 1939. There were more than 75000 people in the audience, along with the people who listened to the radio broadcast. In the crowd, there were people of all color, with no segregation.
The excerpt "How would Anderson like to sing on Easter Sunday at the Lincoln Memorial? It would be an outdoor concert, free, open to all—and with no segregation." refers to this event and the fact that people of all colors attended and eased the racial discrimination of African Americans that was very present in the US at the time.
The expert "But across the footlights Anderson often saw only white faces. In many cities, in the South especially, people of her own race had to sit up in the balcony." shows exactly opposite - that all other concerts that Anderson held were segregated, with special seats for African Americans, and mostly populated by white people.
The final excerpt ("When her tour schedule brought her to Washington, D.C., in 1939, the choice was obvious: the city’s largest and grandest concert venue, Constitution Hall. Anderson’s manager wrote to make arrangements" ) refers to Anderson's success and the fact she was filling up the largest halls in the country, even in the capital.