What did the montgomery bus boycott teach civil rights activists in montgomery and elsewhere?
one person could make a difference.
segregation laws could be changed.
nonviolent resistance could inspire a violent response.
nonviolent resistance could succeed in ending segregation.

Nonviolent resistance could succeed in ending segregation  is the right answer

Explanation:

A 13 month mass protest of bus boycott in the year 1955 with the arrest of Rosa Park in USA is known as the Montgomery Bus Boycott. In the leadership of Martin Luther, the boycott is an example of successful abolishing of segregation through nonviolent protest. This protest led the Supreme Court’s decision on un-constitutionalism of public buses.

It gained support outside the Montgomery. With the end of the boycott the segregated sitting in buses were removed by the laws of the Supreme Court.  

the doctrine of nullification recommended that states living inside the union have the one-sided, inalienable ideal to void any law made by the national government that could be esteemed illegal.

the united states was shaped based on a general agreement among its individual states. hence, it is inferred that under the hypothesis of invalidation, since the states are the establishment of the union, they have the ability to referee and disprove unlawful laws.

health care plans in the united states having high costs because they are focusing on providing quality programs for different groups of individuals. the quality of the service is based on money flow received from the members. without this investment, couldn't be possible a constant scientific searching to prevent death and illness caused because of low levels of health investigation. currently, the complaints are not about the highest cost, but about the coverage and benefits to access the necessary health services required by the members.  

besides, if a global health system is established the quality levels will fall down because of the standardized of the health. the access to care will increase but the quality will be low because it depends on the money invested.