Which statement best describes the introduction of an argumentative essay?

Which statement best describes the introduction of an argumentative essay?

a. It acquaints readers with the topic and sets up the ideas that will be presented.
b. It establishes the main point of the essay and tells readers what the writer’s position is.
c. It ties the essay together and tells readers what they have learned and should take away.
d. It fleshes out the argument and includes counterclaims and evidence from research.