The main purpose of each of these excerpts is:
C. to declare the intentions of the writers and their purpose for writing.
In the excerpt from the Magna Carta, the focus is on establishing the freedom of the English Church and affirming the rights and liberties it should hold. In the Declaration of the Rights of Man, the representatives articulate their intention to outline the natural and sacred rights of man to protect those rights and to guide the actions of the legislative and executive powers. Both documents clearly aim to express the goals and principles that the authors seek to establish.