The section that most clearly indicates the main purpose of the Constitution's authors is: D. to form a more perfect Union.
In the Preamble to the U.S. Constitution, the authors established their authority on the matter and stated the purpose of the constitution.
Central to the purpose of the constitution was forming a more perfect union among the states.
Thus, option D correctly stated the main purpose of the authors of the constitution.
Learn more about the preamble to the U.S. Constitution here:
https://brainly.com/question/4397075