Answer:
1. C
2. A or C
3. The point that the boycott made the bus company was that without them, the bus would practically go bankrupt because they had no business. Therefore, the only way they would go back to riding on the bus is if they were treated all equally, despite the color of their skin.
4. The Montgomery Bus Boycott was significant on several fronts. First, it is widely regarded as the earliest mass protest on behalf of civil rights in the United States, setting the stage for additional large-scale actions outside the court system to bring about fair treatment for African Americans.
I hope I helped, please correct me if I'm wrong!