Which of the following quotes does not use a metaphor?

a) “i have a dream that one day on the red hills of georgia the sons of former slaves and the sons of former slave-owners will be able to sit down together at the table of brotherhood”
b) “i have a dream that my four little children will one day live in a nation where they will not be judged by the color of their skin but by the content of their character.”
c) “i have a dream that one day even the state of mississippi, a state sweltering with the heat of injustice, sweltering with the heat of oppression, will be transformed into an oasis of freedom and justice.”
d) “four score and seven years ago our fathers brought forth on this continent, a new nation, conceived in liberty, and dedicated to the proposition that all men are created equal.”