Final answer:
The concession mentioned in the context implies that the author acknowledges valid points in the opposing argument, known as a concession, and further strengthens their own argument, or nonclusion.
Step-by-step explanation:
The concession an author makes to an opposing argument refers to acknowledging valid points from the other side. If paragraph 14 includes a concession, the author is recognizing that there are some merits to the counterarguments but still believes their own argument to be stronger. Based on the information provided, where concession and nonclusion are mentioned as an inseparable pair, a well-crafted argument would present a concession to show fairness and understanding of the opposing view. This is often followed by a nonclusion, further proving the author's point, and demonstrating the author's rhetorical skill and logical appeal.
From the options available and keeping the provided context in mind, the most accurate answer is b) the author concedes that there are valid points in the opposing argument. This is because the text guides on making concessions while also emphasizing on strengthening one's own argument by addressing the concession with a nonclusion.