Answer: The purpose of the Bill of Rights is revealed in the infinitive phrase.
Step-by-step explanation: An infinitive phrase is a group of words that contains the infinitive "to" and the simple form of a verb. In the excerpt provided, "to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defense, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity" is an infinitive phrase since it includes the infinitive "to" plus the simple form of different verbs. Moreover, this infinitive phrase reveals the purpose of the Bill of Rights, that is to say it reveals the goals that the authors wanted to achieve with the drafting of this document.