Why would this idea have been important to the
authors of the declaration of independence?

The Declaration of Independence was written to act as an explanation to the international community the reasons why the colonies were declaring their independence from England. A declaration of independence was bound to elicit an aggressive reaction from Great Britain, which was keen to maintain its hold on America.

Explanation:

no statements but ok.

the statement that best describes the idea of manifest destiny that was used in the 19th century would be that "it was fate that the united states would continue to  expand westward," since people thought the us was "destined" to do so. 

b, the anti immigrant fervor