Final answer:
Dr. Martin Luther King Jr. became involved in the bus boycott in Montgomery, Alabama as the leader of the protest.
Step-by-step explanation:
Dr. Martin Luther King Jr. became involved in the bus boycott in Montgomery, Alabama when he was chosen to lead the protest. As a young minister and the leader of the Montgomery Improvement Association, he played a pivotal role in organizing the boycott and rallying the African American community. The boycott lasted for 381 days and resulted in the Supreme Court ruling that bus segregation was unconstitutional.