Which group of people gained power as a
result of independence from the United
Kingdom?

The Second Continental Congress

Explanation:

I see no options but the answer might be the Second Continental Congress. This Congress was the de-facto National Government of the Colonies through the American Revolution. In 1776 they declared the Independence of the Colonies and stated themselves to be Independent states.

The Congress was composed of representatives from the various colonies and were able to coordinate the American response to the British. They raised armies, navies and even a postal service and passed the first Constitution being the Articles of Confederation in 1781.

the answer to your question is:

strong-mayor system