Which best describes the structure of the declaration of independence?

The correct answer for the question that is being presented above is this one: "B. The purpose was tell why the colonies were revolting against Britain and declaring their independence."

Here are the following choices:
A. The purpose was to insult the King of England.
B. The purpose was tell why the colonies were revolting against Britain and declaring their independence.
C. The purpose was to describe ways that the colonists could improve themselves.