Final answer:
Dr. Martin Luther King Jr. establishes his authority by alluding to the revered document, the U.S. Declaration of Independence, referencing foundational American principles of equality and unalienable rights.
Step-by-step explanation:
In the excerpt provided, Dr. Martin Luther King Jr. establishes his authority by alluding to a revered document, which is the United States Declaration of Independence. King references the foundational American principle that "all men are created equal" and have unalienable rights such as "Life, Liberty and the pursuit of Happiness." These concepts were articulated by Thomas Jefferson, a notable historical figure, which lends weight and historical significance to King's argument for equality and civil rights.
In doing this, King is not only appealing to the patriotic ethos and the foundational values of the American nation, but also positioning himself within a long-standing political and ethical argument for human rights and equality. The correct option for establishing authority in the sentence in question is (b) He alludes to a revered document.