Final answer:
The Montgomery Improvement Association was led by Dr. Martin Luther King Jr. in the 1950s after Rosa Parks' arrest, and they organized the successful Montgomery Bus Boycott.
Step-by-step explanation:
The Montgomery Improvement Association (MIA) was created in the 1950s following Rosa Parks' defiance against segregation laws. The association was led by Dr. Martin Luther King Jr., who was elected as its president and became the spokesperson for the Civil Rights Movement. The MIA played a pivotal role in orchestrating the Montgomery Bus Boycott, which lasted for 381 days and led to a Supreme Court ruling that ended the segregation on public buses.