The correct answer is:
C. Body paragraph three
A counterargument is an Argument that disagrees with or opposes with another argument. The reason why you should address your counterargument at this point of the essay, is because before of it you should introduce your topic, argument and supporting detail, assigned to go on body paragraph one, and two respectively. The concluding paragraph is used to summarize what you said in your thesis statement, not to oppose to any idea.