Step-by-step explanation:
According to the preamble, the phrase "a more perfect Union" refers to option A, improving upon a previous attempt at creating a new union. The preamble states that the purpose of the Constitution is to "form a more perfect Union," which suggests that the framers of the Constitution believed that there were flaws in the previous attempt at creating a union (the Articles of Confederation) and that they sought to improve upon it with the new Constitution.