The answer is option A "a belief that the United States had a duty or destiny to expand westward." When the Manifest Destiny began the settlers thought that God himself told them to expand, so they though that God gave them a duty to expand westward and many people thought it was their destiny to carry out God's will.
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King George kept MA under martial law and appointed General Thomas Gage as the new governor. He wanted to keep them from acting out against England.
It permanently shifted the global balance of power.
Negotiation is the main output. They should join the countries that have been victims of this group and seek solutions through peaceful means. The above is achieved with sufficient commitment. It is a titanic task but not impossible. The largest number of nations in the world must be allied to coordinate actions of a military nature. One can also think of a diplomatic solution to the eventual failure due to possible military action.