Final answer:
Rosa Parks refused to give up her seat on a Montgomery bus in 1955, leading to the historic Montgomery Bus Boycott, which contributed significantly to the Civil Rights Movement and ended with the Supreme Court ruling that segregated buses were unconstitutional.
Step-by-step explanation:
The woman who sparked a bus boycott by refusing to give up her seat in Montgomery, AL, in 1955, was Rosa Parks. On December 1, 1955, her act of defiance against racial segregation made national headlines and ignited the Montgomery Bus Boycott. This event became a monumental part of the Civil Rights Movement, with leaders like Martin Luther King Jr. and the Women's Political Council playing critical roles in the campaign against racial discrimination on public transit. The boycott lasted for 381 days and led to a Supreme Court decision that declared the Alabama and Montgomery laws requiring segregated buses unconstitutional.