Final answer:
The focus on Ms. Parks' reason for starting the Montgomery Bus Boycott highlights the significance of her act and the injustice faced by African Americans.
Step-by-step explanation:
The focus on Ms. Parks' reason for starting the Montgomery Bus Boycott of 1955-1956 suggests that her act of refusing to give up her seat to a white person was significant and served as a catalyst for the boycott.
By highlighting her decision and the subsequent arrest and court case, the author emphasizes the injustice and inequality that African Americans faced on the bus system.
This event, coupled with the efforts of other leaders and organizations, led to a united protest against the policy of racial segregation.