The second body paragraph.
When constructing an argumentative/persuasive essay or speech, the order of paragraphs will be the introduction (which will contain the hook, background, and thesis), the body, which will contain the support and counterarguments (which will be refuted), and then the conclusion. Given that the first body paragraph is technically the second paragraph, which is the support for your topic/position, and the counterargument should follow the support, the counterargument should be the second body paragraph (or third paragraph overall).
